Prefer subtypes of Multimap

Guava team recommends using the subinterfaces of Multimap, for the
same reasons they recommend using Set and List rather than Collection:
it documents expectations about ordering, uniqueness, and behavior of
equals. Do this across the board in Gerrit.

Mostly this is straightforward and I tried to exactly match existing
behavior where possible. However, there were a few wrinkles, where
different callers passed different subtypes to the same method.

The main one is arguments to ParameterParser#parse and
splitQueryString, where some callers used SetMultimaps (perhaps
semi-intentionally, or perhaps misunderstanding the nature of
HashMultimap). For the purposes of parameter parsing, a ListMultimap
makes more sense, because it preserves argument order and repetition.

Another instance is a couple places in ReceiveCommits and downstream
where there were SetMultimap<?, Ref>. Since Refs do not implement
equals, this is effectively the same thing as a ListMultimap, and
changing the interface no longer misleads readers into thinking there
might be some deduplication happening.

Finally, this change includes a breaking API change to the return
type of ExternalIncludedIn#getIncludedIn.

Change-Id: I5f1d15e27a32e534a6aaefe204e7a31815f4c8d7

gerrit-acceptance-framework/src/test/java/com/google/gerrit/acceptance/EventRecorder.java

@@ -19,7 +19,7 @@ import static com.google.common.truth.Truth.assertThat;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.LinkedListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.UserScopedEventListener;
 import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.extensions.registration.RegistrationHandle;
@@ -39,7 +39,7 @@ import org.eclipse.jgit.revwalk.RevCommit;
 
 public class EventRecorder {
   private final RegistrationHandle eventListenerRegistration;
-  private final Multimap<String, RefEvent> recordedEvents;
+  private final ListMultimap<String, RefEvent> recordedEvents;
 
   @Singleton
   public static class Factory {

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/config/ExternalIncludedIn.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.extensions.config;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.annotations.ExtensionPoint;
 
 import java.util.Collection;
@@ -37,6 +37,6 @@ public interface ExternalIncludedIn {
    * @param branches the branches that include the commit
    * @return additional entries for IncludedInInfo
    */
-  Multimap<String, String> getIncludedIn(String project, String commit,
+  ListMultimap<String, String> getIncludedIn(String project, String commit,
       Collection<String> tags, Collection<String> branches);
 }

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/restapi/NeedsParams.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.extensions.restapi;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 
 /**
  * Optional interface for {@link RestCollection}.
@@ -28,5 +28,5 @@ public interface NeedsParams {
    *
    * @param params the request parameter
    */
-  void setParams(Multimap<String, String> params) throws RestApiException;
+  void setParams(ListMultimap<String, String> params) throws RestApiException;
 }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/plugins/HttpAutoRegisterModuleGenerator.java

@@ -17,7 +17,7 @@ package com.google.gerrit.httpd.plugins;
 import static com.google.gerrit.server.plugins.AutoRegisterUtil.calculateBindAnnotation;
 
 import com.google.common.collect.LinkedListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.annotations.Export;
 import com.google.gerrit.server.plugins.InvalidPluginException;
 import com.google.gerrit.server.plugins.ModuleGenerator;
@@ -35,7 +35,8 @@ import javax.servlet.http.HttpServlet;
 class HttpAutoRegisterModuleGenerator extends ServletModule
     implements ModuleGenerator {
   private final Map<String, Class<HttpServlet>> serve = new HashMap<>();
-  private final Multimap<TypeLiteral<?>, Class<?>> listeners = LinkedListMultimap.create();
+  private final ListMultimap<TypeLiteral<?>, Class<?>> listeners =
+      LinkedListMultimap.create();
 
   @Override
   protected void configureServlets() {

gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java

@@ -23,7 +23,7 @@ import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.extensions.restapi.Url;
@@ -59,7 +59,7 @@ class ParameterParser {
   }
 
   <T> boolean parse(T param,
-      Multimap<String, String> in,
+      ListMultimap<String, String> in,
       HttpServletRequest req,
       HttpServletResponse res)
       throws IOException {
@@ -90,8 +90,8 @@ class ParameterParser {
   }
 
   static void splitQueryString(String queryString,
-      Multimap<String, String> config,
+      ListMultimap<String, String> config,
-      Multimap<String, String> params) {
+      ListMultimap<String, String> params) {
     if (!Strings.isNullOrEmpty(queryString)) {
       for (String kvPair : Splitter.on('&').split(queryString)) {
         Iterator<String> i = Splitter.on('=').limit(2).split(kvPair).iterator();

gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java

@@ -45,13 +45,13 @@ import com.google.common.base.CharMatcher;
 import com.google.common.base.Joiner;
 import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
+import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.LinkedHashMultimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 import com.google.common.io.BaseEncoding;
 import com.google.common.io.CountingOutputStream;
 import com.google.common.math.IntMath;
@@ -245,8 +245,8 @@ public class RestApiServlet extends HttpServlet {
     int status = SC_OK;
     long responseBytes = -1;
     Object result = null;
-    Multimap<String, String> params = LinkedHashMultimap.create();
+    ListMultimap<String, String> params = ArrayListMultimap.create();
-    Multimap<String, String> config = LinkedHashMultimap.create();
+    ListMultimap<String, String> config = ArrayListMultimap.create();
     Object inputRequestBody = null;
     RestResource rsrc = TopLevelResource.INSTANCE;
     ViewData viewData = null;
@@ -460,9 +460,9 @@ public class RestApiServlet extends HttpServlet {
           metric,
           System.nanoTime() - startNanos,
           TimeUnit.NANOSECONDS);
-      globals.auditService.dispatch(new ExtendedHttpAuditEvent(globals.webSession.get()
+      globals.auditService.dispatch(new ExtendedHttpAuditEvent(
-          .getSessionId(), globals.currentUser.get(), req,
+          globals.webSession.get().getSessionId(), globals.currentUser.get(),
-          auditStartTs, params, inputRequestBody, status,
+          req, auditStartTs, params, inputRequestBody, status,
           result, rsrc, viewData == null ? null : viewData.view));
     }
   }
@@ -777,7 +777,7 @@ public class RestApiServlet extends HttpServlet {
 
   public static long replyJson(@Nullable HttpServletRequest req,
       HttpServletResponse res,
-      Multimap<String, String> config,
+      ListMultimap<String, String> config,
       Object result)
       throws IOException {
     TemporaryBuffer.Heap buf = heap(HEAP_EST_SIZE, Integer.MAX_VALUE);
@@ -796,7 +796,7 @@ public class RestApiServlet extends HttpServlet {
       .setCharacterEncoding(UTF_8));
   }
 
-  private static Gson newGson(Multimap<String, String> config,
+  private static Gson newGson(ListMultimap<String, String> config,
       @Nullable HttpServletRequest req) {
     GsonBuilder gb = OutputFormat.JSON_COMPACT.newGsonBuilder();
 
@@ -807,7 +807,7 @@ public class RestApiServlet extends HttpServlet {
   }
 
   private static void enablePrettyPrint(GsonBuilder gb,
-      Multimap<String, String> config,
+      ListMultimap<String, String> config,
       @Nullable HttpServletRequest req) {
     String pp = Iterables.getFirst(config.get("pp"), null);
     if (pp == null) {
@@ -822,7 +822,7 @@ public class RestApiServlet extends HttpServlet {
   }
 
   private static void enablePartialGetFields(GsonBuilder gb,
-      Multimap<String, String> config) {
+      ListMultimap<String, String> config) {
     final Set<String> want = new HashSet<>();
     for (String p : config.get("fields")) {
       Iterables.addAll(want, OptionUtil.splitOptionValue(p));
@@ -1130,7 +1130,8 @@ public class RestApiServlet extends HttpServlet {
   static long replyText(@Nullable HttpServletRequest req,
       HttpServletResponse res, String text) throws IOException {
     if ((req == null || isRead(req)) && isMaybeHTML(text)) {
-      return replyJson(req, res, ImmutableMultimap.of("pp", "0"), new JsonPrimitive(text));
+      return replyJson(req, res, ImmutableListMultimap.of("pp", "0"),
+          new JsonPrimitive(text));
     }
     if (!text.endsWith("\n")) {
       text += "\n";

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/GerritJsonServlet.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.httpd.rpc;
 
 import com.google.common.collect.ArrayListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.audit.AuditService;
 import com.google.gerrit.audit.RpcAuditEvent;
 import com.google.gerrit.common.TimeUtil;
@@ -133,25 +133,28 @@ final class GerritJsonServlet extends JsonServlet<GerritJsonServlet.GerritCall>
       }
       Audit note = method.getAnnotation(Audit.class);
       if (note != null) {
-        final String sid = call.getWebSession().getSessionId();
+        String sid = call.getWebSession().getSessionId();
-        final CurrentUser username = call.getWebSession().getUser();
+        CurrentUser username = call.getWebSession().getUser();
-        final Multimap<String, ?> args =
+        ListMultimap<String, ?> args = extractParams(note, call);
-            extractParams(note, call);
+        String what = extractWhat(note, call);
-        final String what = extractWhat(note, call);
+        Object result = call.getResult();
-        final Object result = call.getResult();
 
-        audit.dispatch(new RpcAuditEvent(sid, username, what, call.getWhen(),
+        audit.dispatch(
-            args, call.getHttpServletRequest().getMethod(), call.getHttpServletRequest().getMethod(),
+            new RpcAuditEvent(
-            ((AuditedHttpServletResponse) (call.getHttpServletResponse()))
+                sid, username, what, call.getWhen(), args,
-                .getStatus(), result));
+                call.getHttpServletRequest().getMethod(),
+                call.getHttpServletRequest().getMethod(),
+                ((AuditedHttpServletResponse) (call.getHttpServletResponse()))
+                    .getStatus(),
+                result));
       }
     } catch (Throwable all) {
       log.error("Unable to log the call", all);
     }
   }
 
-  private Multimap<String, ?> extractParams(final Audit note, final GerritCall call) {
+  private ListMultimap<String, ?> extractParams(Audit note, GerritCall call) {
-    Multimap<String, Object> args = ArrayListMultimap.create();
+    ListMultimap<String, Object> args = ArrayListMultimap.create();
 
     Object[] params = call.getParams();
     for (int i = 0; i < params.length; i++) {

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/doc/QueryDocumentationFilter.java

@@ -15,8 +15,7 @@
 package com.google.gerrit.httpd.rpc.doc;
 
 import com.google.common.base.Strings;
-import com.google.common.collect.LinkedHashMultimap;
+import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
 import com.google.gerrit.httpd.restapi.RestApiServlet;
 import com.google.gerrit.server.documentation.QueryDocumentationExecutor;
 import com.google.gerrit.server.documentation.QueryDocumentationExecutor.DocQueryException;
@@ -68,8 +67,7 @@ public class QueryDocumentationFilter implements Filter {
       HttpServletResponse rsp = (HttpServletResponse) response;
       try {
         List<DocResult> result = searcher.doQuery(request.getParameter("q"));
-        Multimap<String, String> config = LinkedHashMultimap.create();
+        RestApiServlet.replyJson(req, rsp, ImmutableListMultimap.of(), result);
-        RestApiServlet.replyJson(req, rsp, config, result);
       } catch (DocQueryException e) {
         log.error("Doc search failed:", e);
         rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneChangeIndex.java

@@ -28,7 +28,7 @@ import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Sets;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListeningExecutorService;
@@ -408,9 +408,9 @@ public class LuceneChangeIndex implements ChangeIndex {
     }
   }
 
-  private static Multimap<String, IndexableField> fields(Document doc,
+  private static ListMultimap<String, IndexableField> fields(Document doc,
       Set<String> fields) {
-    Multimap<String, IndexableField> stored =
+    ListMultimap<String, IndexableField> stored =
         ArrayListMultimap.create(fields.size(), 4);
     for (IndexableField f : doc) {
       String name = f.name();
@@ -421,7 +421,7 @@ public class LuceneChangeIndex implements ChangeIndex {
     return stored;
   }
 
-  private ChangeData toChangeData(Multimap<String, IndexableField> doc,
+  private ChangeData toChangeData(ListMultimap<String, IndexableField> doc,
       Set<String> fields, String idFieldName) {
     ChangeData cd;
     // Either change or the ID field was guaranteed to be included in the call
@@ -482,7 +482,8 @@ public class LuceneChangeIndex implements ChangeIndex {
     return cd;
   }
 
-  private void decodePatchSets(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodePatchSets(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     List<PatchSet> patchSets =
         decodeProtos(doc, PATCH_SET_FIELD, PatchSetProtoField.CODEC);
     if (!patchSets.isEmpty()) {
@@ -492,12 +493,14 @@ public class LuceneChangeIndex implements ChangeIndex {
     }
   }
 
-  private void decodeApprovals(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodeApprovals(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     cd.setCurrentApprovals(
         decodeProtos(doc, APPROVAL_FIELD, PatchSetApprovalProtoField.CODEC));
   }
 
-  private void decodeChangedLines(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodeChangedLines(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     IndexableField added = Iterables.getFirst(doc.get(ADDED_FIELD), null);
     IndexableField deleted = Iterables.getFirst(doc.get(DELETED_FIELD), null);
     if (added != null && deleted != null) {
@@ -513,7 +516,8 @@ public class LuceneChangeIndex implements ChangeIndex {
     }
   }
 
-  private void decodeMergeable(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodeMergeable(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     IndexableField f = Iterables.getFirst(doc.get(MERGEABLE_FIELD), null);
     if (f != null) {
       String mergeable = f.stringValue();
@@ -525,7 +529,8 @@ public class LuceneChangeIndex implements ChangeIndex {
     }
   }
 
-  private void decodeReviewedBy(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodeReviewedBy(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     Collection<IndexableField> reviewedBy = doc.get(REVIEWEDBY_FIELD);
     if (reviewedBy.size() > 0) {
       Set<Account.Id> accounts =
@@ -541,7 +546,8 @@ public class LuceneChangeIndex implements ChangeIndex {
     }
   }
 
-  private void decodeHashtags(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodeHashtags(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     Collection<IndexableField> hashtag = doc.get(HASHTAG_FIELD);
     Set<String> hashtags = Sets.newHashSetWithExpectedSize(hashtag.size());
     for (IndexableField r : hashtag) {
@@ -550,9 +556,10 @@ public class LuceneChangeIndex implements ChangeIndex {
     cd.setHashtags(hashtags);
   }
 
-  private void decodeStar(Multimap<String, IndexableField> doc, ChangeData cd) {
+  private void decodeStar(ListMultimap<String, IndexableField> doc,
+      ChangeData cd) {
     Collection<IndexableField> star = doc.get(STAR_FIELD);
-    Multimap<Account.Id, String> stars = ArrayListMultimap.create();
+    ListMultimap<Account.Id, String> stars = ArrayListMultimap.create();
     for (IndexableField r : star) {
       StarredChangesUtil.StarField starField =
           StarredChangesUtil.StarField.parse(r.stringValue());
@@ -563,7 +570,7 @@ public class LuceneChangeIndex implements ChangeIndex {
     cd.setStars(stars);
   }
 
-  private void decodeReviewers(Multimap<String, IndexableField> doc,
+  private void decodeReviewers(ListMultimap<String, IndexableField> doc,
       ChangeData cd) {
     cd.setReviewers(
         ChangeField.parseReviewerFieldValues(
@@ -571,7 +578,7 @@ public class LuceneChangeIndex implements ChangeIndex {
                 .transform(IndexableField::stringValue)));
   }
 
-  private void decodeSubmitRecords(Multimap<String, IndexableField> doc,
+  private void decodeSubmitRecords(ListMultimap<String, IndexableField> doc,
       String field, SubmitRuleOptions opts, ChangeData cd) {
     ChangeField.parseSubmitRecords(
         Collections2.transform(
@@ -579,17 +586,18 @@ public class LuceneChangeIndex implements ChangeIndex {
         opts, cd);
   }
 
-  private void decodeRefStates(Multimap<String, IndexableField> doc,
+  private void decodeRefStates(ListMultimap<String, IndexableField> doc,
       ChangeData cd) {
     cd.setRefStates(copyAsBytes(doc.get(REF_STATE_FIELD)));
   }
 
-  private void decodeRefStatePatterns(Multimap<String, IndexableField> doc,
+  private void decodeRefStatePatterns(ListMultimap<String, IndexableField> doc,
       ChangeData cd) {
     cd.setRefStatePatterns(copyAsBytes(doc.get(REF_STATE_PATTERN_FIELD)));
   }
 
-  private static <T> List<T> decodeProtos(Multimap<String, IndexableField> doc,
+  private static <T> List<T> decodeProtos(
+      ListMultimap<String, IndexableField> doc,
       String fieldName, ProtobufCodec<T> codec) {
     Collection<IndexableField> fields = doc.get(fieldName);
     if (fields.isEmpty()) {

gerrit-pgm/src/main/java/com/google/gerrit/pgm/RebuildNoteDb.java

@@ -21,9 +21,9 @@ import static com.google.gerrit.server.schema.DataSourceProvider.Context.MULTI_U
 import com.google.common.base.Predicates;
 import com.google.common.base.Stopwatch;
 import com.google.common.collect.ArrayListMultimap;
-import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Ordering;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
@@ -153,7 +153,7 @@ public class RebuildNoteDb extends SiteProgram {
     ListeningExecutorService executor = newExecutor();
     System.out.println("Rebuilding the NoteDb");
 
-    final ImmutableMultimap<Project.NameKey, Change.Id> changesByProject =
+    ImmutableListMultimap<Project.NameKey, Change.Id> changesByProject =
         getChangesByProject();
     boolean ok;
     Stopwatch sw = Stopwatch.createStarted();
@@ -241,11 +241,11 @@ public class RebuildNoteDb extends SiteProgram {
     return MoreExecutors.newDirectExecutorService();
   }
 
-  private ImmutableMultimap<Project.NameKey, Change.Id> getChangesByProject()
+  private ImmutableListMultimap<Project.NameKey, Change.Id> getChangesByProject()
       throws OrmException {
     // Memorize all changes so we can close the db connection and allow
     // rebuilder threads to use the full connection pool.
-    Multimap<Project.NameKey, Change.Id> changesByProject =
+    ListMultimap<Project.NameKey, Change.Id> changesByProject =
         ArrayListMultimap.create();
     try (ReviewDb db = schemaFactory.open()) {
       if (projects.isEmpty() && !changes.isEmpty()) {
@@ -270,12 +270,12 @@ public class RebuildNoteDb extends SiteProgram {
           }
         }
       }
-      return ImmutableMultimap.copyOf(changesByProject);
+      return ImmutableListMultimap.copyOf(changesByProject);
     }
   }
 
   private boolean rebuildProject(ReviewDb db,
-      ImmutableMultimap<Project.NameKey, Change.Id> allChanges,
+      ImmutableListMultimap<Project.NameKey, Change.Id> allChanges,
       Project.NameKey project, Repository allUsersRepo)
       throws IOException, OrmException {
     checkArgument(allChanges.containsKey(project));

gerrit-server/src/main/java/com/google/gerrit/audit/AuditEvent.java

@@ -17,22 +17,22 @@ package com.google.gerrit.audit;
 import com.google.auto.value.AutoValue;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.MultimapBuilder;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.server.CurrentUser;
 
 public class AuditEvent {
 
   public static final String UNKNOWN_SESSION_ID = "000000000000000000000000000";
-  protected static final Multimap<String, ?> EMPTY_PARAMS =
+  protected static final ListMultimap<String, ?> EMPTY_PARAMS =
-      MultimapBuilder.hashKeys().hashSetValues().build();
+      ImmutableListMultimap.of();
 
   public final String sessionId;
   public final CurrentUser who;
   public final long when;
   public final String what;
-  public final Multimap<String, ?> params;
+  public final ListMultimap<String, ?> params;
   public final Object result;
   public final long timeAtStart;
   public final long elapsed;
@@ -59,7 +59,7 @@ public class AuditEvent {
    * @param result result of the event
    */
   public AuditEvent(String sessionId, CurrentUser who, String what, long when,
-      Multimap<String, ?> params, Object result) {
+      ListMultimap<String, ?> params, Object result) {
     Preconditions.checkNotNull(what, "what is a mandatory not null param !");
 
     this.sessionId = MoreObjects.firstNonNull(sessionId, UNKNOWN_SESSION_ID);

gerrit-server/src/main/java/com/google/gerrit/audit/ExtendedHttpAuditEvent.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.audit;
 
 import com.google.common.base.Preconditions;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.restapi.RestResource;
 import com.google.gerrit.extensions.restapi.RestView;
 import com.google.gerrit.server.CurrentUser;
@@ -45,11 +45,11 @@ public class ExtendedHttpAuditEvent extends HttpAuditEvent {
    * @param view view rendering object
    */
   public ExtendedHttpAuditEvent(String sessionId, CurrentUser who,
-      HttpServletRequest httpRequest, long when, Multimap<String, ?> params,
+      HttpServletRequest httpRequest, long when, ListMultimap<String, ?> params,
       Object input, int status, Object result, RestResource resource,
       RestView<RestResource> view) {
-    super(sessionId, who, httpRequest.getRequestURI(), when, params, httpRequest.getMethod(),
+    super(sessionId, who, httpRequest.getRequestURI(), when, params,
-        input, status, result);
+        httpRequest.getMethod(), input, status, result);
     this.httpRequest = Preconditions.checkNotNull(httpRequest);
     this.resource = resource;
     this.view = view;

gerrit-server/src/main/java/com/google/gerrit/audit/HttpAuditEvent.java

@@ -13,7 +13,7 @@
 // limitations under the License.
 package com.google.gerrit.audit;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.server.CurrentUser;
 
 public class HttpAuditEvent extends AuditEvent {
@@ -34,8 +34,9 @@ public class HttpAuditEvent extends AuditEvent {
    * @param status HTTP status
    * @param result result of the event
    */
-  public HttpAuditEvent(String sessionId, CurrentUser who, String what, long when,
+  public HttpAuditEvent(String sessionId, CurrentUser who, String what,
-      Multimap<String, ?> params, String httpMethod, Object input, int status, Object result) {
+      long when, ListMultimap<String, ?> params, String httpMethod,
+      Object input, int status, Object result) {
     super(sessionId, who, what, when, params, result);
     this.httpMethod = httpMethod;
     this.input = input;

gerrit-server/src/main/java/com/google/gerrit/audit/RpcAuditEvent.java

@@ -11,9 +11,10 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
 package com.google.gerrit.audit;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.server.CurrentUser;
 
 public class RpcAuditEvent extends HttpAuditEvent {
@@ -32,8 +33,8 @@ public class RpcAuditEvent extends HttpAuditEvent {
    * @param result result of the event
    */
   public RpcAuditEvent(String sessionId, CurrentUser who, String what,
-      long when, Multimap<String, ?> params, String httpMethod, Object input,
+      long when, ListMultimap<String, ?> params, String httpMethod,
-      int status, Object result) {
+      Object input, int status, Object result) {
     super(sessionId, who, what, when, params, httpMethod, input, status, result);
   }
 }

gerrit-server/src/main/java/com/google/gerrit/audit/SshAuditEvent.java

@@ -11,15 +11,16 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
 package com.google.gerrit.audit;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.server.CurrentUser;
 
 public class SshAuditEvent extends AuditEvent {
 
   public SshAuditEvent(String sessionId, CurrentUser who, String what,
-      long when, Multimap<String, ?> params, Object result) {
+      long when, ListMultimap<String, ?> params, Object result) {
     super(sessionId, who, what, when, params, result);
   }
 }

gerrit-server/src/main/java/com/google/gerrit/rules/PredicateClassLoader.java

@@ -11,10 +11,11 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
 package com.google.gerrit.rules;
 
 import com.google.common.collect.LinkedHashMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.SetMultimap;
 import com.google.gerrit.extensions.registration.DynamicSet;
 
 import java.util.Collection;
@@ -24,7 +25,7 @@ import java.util.Collection;
  */
 public class PredicateClassLoader extends ClassLoader {
 
-  private final Multimap<String, ClassLoader> packageClassLoaderMap =
+  private final SetMultimap<String, ClassLoader> packageClassLoaderMap =
       LinkedHashMultimap.create();
 
   public PredicateClassLoader(

gerrit-server/src/main/java/com/google/gerrit/server/StarredChangesUtil.java

@@ -23,8 +23,8 @@ import com.google.auto.value.AutoValue;
 import com.google.common.base.CharMatcher;
 import com.google.common.base.Joiner;
 import com.google.common.base.Splitter;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.primitives.Ints;
@@ -314,7 +314,7 @@ public class StarredChangesUtil {
     }
   }
 
-  public ImmutableMultimap<Account.Id, String> byChangeFromIndex(
+  public ImmutableListMultimap<Account.Id, String> byChangeFromIndex(
       Change.Id changeId) throws OrmException {
     Set<String> fields = ImmutableSet.of(
         ChangeField.ID.getName(),

gerrit-server/src/main/java/com/google/gerrit/server/account/ExternalIdCacheImpl.java

@@ -17,7 +17,7 @@ package com.google.gerrit.server.account;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableSetMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.AccountExternalId;
@@ -76,7 +76,7 @@ public class ExternalIdCacheImpl implements ExternalIdCache {
   public void onCreate(Iterable<AccountExternalId> extIds) {
     lock.lock();
     try {
-      Multimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
+      ListMultimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
           .arrayListValues().build(extIdsByAccount.get(AllKey.ALL));
       for (AccountExternalId extId : extIds) {
         n.put(extId.getAccountId(), extId);
@@ -93,7 +93,7 @@ public class ExternalIdCacheImpl implements ExternalIdCache {
   public void onRemove(Iterable<AccountExternalId> extIds) {
     lock.lock();
     try {
-      Multimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
+      ListMultimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
           .arrayListValues().build(extIdsByAccount.get(AllKey.ALL));
       for (AccountExternalId extId : extIds) {
         n.remove(extId.getAccountId(), extId);
@@ -111,7 +111,7 @@ public class ExternalIdCacheImpl implements ExternalIdCache {
       Iterable<AccountExternalId.Key> extIdKeys) {
     lock.lock();
     try {
-      Multimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
+      ListMultimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
           .arrayListValues().build(extIdsByAccount.get(AllKey.ALL));
       for (AccountExternalId extId : byAccount(accountId)) {
         for (AccountExternalId.Key extIdKey : extIdKeys) {
@@ -133,7 +133,7 @@ public class ExternalIdCacheImpl implements ExternalIdCache {
   public void onUpdate(AccountExternalId updatedExtId) {
     lock.lock();
     try {
-      Multimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
+      ListMultimap<Account.Id, AccountExternalId> n = MultimapBuilder.hashKeys()
           .arrayListValues().build(extIdsByAccount.get(AllKey.ALL));
       for (AccountExternalId extId : byAccount(updatedExtId.getAccountId())) {
         if (updatedExtId.getKey().equals(extId.getKey())) {
@@ -181,7 +181,7 @@ public class ExternalIdCacheImpl implements ExternalIdCache {
     public ImmutableSetMultimap<Account.Id, AccountExternalId> load(AllKey key)
         throws Exception {
       try (ReviewDb db = schema.open()) {
-        Multimap<Account.Id, AccountExternalId> extIdsByAccount =
+        ListMultimap<Account.Id, AccountExternalId> extIdsByAccount =
             MultimapBuilder.hashKeys().arrayListValues().build();
         for (AccountExternalId extId : db.accountExternalIds().all()) {
           extIdsByAccount.put(extId.getAccountId(), extId);

gerrit-server/src/main/java/com/google/gerrit/server/account/UniversalGroupBackend.java

@@ -18,7 +18,7 @@ import static com.google.gerrit.server.account.GroupBackends.GROUP_REF_NAME_COMP
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
@@ -138,7 +138,7 @@ public class UniversalGroupBackend implements GroupBackend {
 
     @Override
     public boolean containsAnyOf(Iterable<AccountGroup.UUID> uuids) {
-      Multimap<GroupMembership, AccountGroup.UUID> lookups =
+      ListMultimap<GroupMembership, AccountGroup.UUID> lookups =
           MultimapBuilder.hashKeys().arrayListValues().build();
       for (AccountGroup.UUID uuid : uuids) {
         if (uuid == null) {
@@ -168,7 +168,7 @@ public class UniversalGroupBackend implements GroupBackend {
 
     @Override
     public Set<AccountGroup.UUID> intersection(Iterable<AccountGroup.UUID> uuids) {
-      Multimap<GroupMembership, AccountGroup.UUID> lookups =
+      ListMultimap<GroupMembership, AccountGroup.UUID> lookups =
           MultimapBuilder.hashKeys().arrayListValues().build();
       for (AccountGroup.UUID uuid : uuids) {
         if (uuid == null) {

gerrit-server/src/main/java/com/google/gerrit/server/account/WatchConfig.java

@@ -25,7 +25,7 @@ import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
@@ -269,7 +269,7 @@ public class WatchConfig extends VersionedMetaData
       cfg.unsetSection(PROJECT, projectName);
     }
 
-    Multimap<String, String> notifyValuesByProject =
+    ListMultimap<String, String> notifyValuesByProject =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (Map.Entry<ProjectWatchKey, Set<NotifyType>> e : projectWatches
         .entrySet()) {

gerrit-server/src/main/java/com/google/gerrit/server/change/Abandon.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.server.change;
 
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.extensions.api.changes.AbandonInput;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
@@ -95,7 +95,7 @@ public class Abandon implements RestModifyView<ChangeResource, AbandonInput>,
 
   public Change abandon(ChangeControl control, String msgTxt,
       NotifyHandling notifyHandling,
-      Multimap<RecipientType, Account.Id> accountsToNotify)
+      ListMultimap<RecipientType, Account.Id> accountsToNotify)
           throws RestApiException, UpdateException {
     CurrentUser user = control.getUser();
     Account account = user.isIdentifiedUser()
@@ -125,7 +125,7 @@ public class Abandon implements RestModifyView<ChangeResource, AbandonInput>,
   public void batchAbandon(Project.NameKey project, CurrentUser user,
       Collection<ChangeControl> controls, String msgTxt,
       NotifyHandling notifyHandling,
-      Multimap<RecipientType, Account.Id> accountsToNotify)
+      ListMultimap<RecipientType, Account.Id> accountsToNotify)
           throws RestApiException, UpdateException {
     if (controls.isEmpty()) {
       return;

gerrit-server/src/main/java/com/google/gerrit/server/change/AbandonUtil.java

@@ -14,8 +14,8 @@
 
 package com.google.gerrit.server.change;
 
-import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.InternalUser;
 import com.google.gerrit.server.config.ChangeCleanupConfig;
@@ -78,15 +78,15 @@ public class AbandonUtil {
               .enforceVisibility(false)
               .query(queryBuilder.parse(query))
               .entities();
-      ImmutableMultimap.Builder<Project.NameKey, ChangeControl> builder =
+      ImmutableListMultimap.Builder<Project.NameKey, ChangeControl> builder =
-          ImmutableMultimap.builder();
+          ImmutableListMultimap.builder();
       for (ChangeData cd : changesToAbandon) {
         ChangeControl control = cd.changeControl(internalUser);
         builder.put(control.getProject().getNameKey(), control);
       }
 
       int count = 0;
-      Multimap<Project.NameKey, ChangeControl> abandons = builder.build();
+      ListMultimap<Project.NameKey, ChangeControl> abandons = builder.build();
       String message = cfg.getAbandonMessage();
       for (Project.NameKey project : abandons.keySet()) {
         Collection<ChangeControl> changes =

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeInserter.java

@@ -21,7 +21,7 @@ import static java.util.stream.Collectors.toSet;
 
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.FooterConstants;
 import com.google.gerrit.common.data.LabelType;
 import com.google.gerrit.common.data.LabelTypes;
@@ -114,7 +114,7 @@ public class ChangeInserter extends BatchUpdate.InsertChangeOp {
   private CommitValidators.Policy validatePolicy =
       CommitValidators.Policy.GERRIT;
   private NotifyHandling notify = NotifyHandling.ALL;
-  private Multimap<RecipientType, Account.Id> accountsToNotify =
+  private ListMultimap<RecipientType, Account.Id> accountsToNotify =
       ImmutableListMultimap.of();
   private Set<Account.Id> reviewers;
   private Set<Account.Id> extraCC;
@@ -240,7 +240,7 @@ public class ChangeInserter extends BatchUpdate.InsertChangeOp {
   }
 
   public ChangeInserter setAccountsToNotify(
-      Multimap<RecipientType, Account.Id> accountsToNotify) {
+      ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     this.accountsToNotify = checkNotNull(accountsToNotify);
     return this;
   }

gerrit-server/src/main/java/com/google/gerrit/server/change/ChangeJson.java

@@ -50,7 +50,6 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
@@ -821,7 +820,7 @@ public class ChangeJson {
     }
 
     Set<String> labelNames = new HashSet<>();
-    Multimap<Account.Id, PatchSetApproval> current =
+    SetMultimap<Account.Id, PatchSetApproval> current =
         MultimapBuilder.hashKeys().hashSetValues().build();
     for (PatchSetApproval a : cd.currentApprovals()) {
       allUsers.add(a.getAccountId());

gerrit-server/src/main/java/com/google/gerrit/server/change/ConsistencyChecker.java

@@ -23,8 +23,8 @@ import static com.google.gerrit.server.ChangeUtil.PS_ID_ORDER;
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
+import com.google.common.collect.SetMultimap;
 import com.google.gerrit.common.FooterConstants;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.TimeUtil;
@@ -126,7 +126,7 @@ public class ConsistencyChecker {
   private RevWalk rw;
 
   private RevCommit tip;
-  private Multimap<ObjectId, PatchSet> patchSetsBySha;
+  private SetMultimap<ObjectId, PatchSet> patchSetsBySha;
   private PatchSet currPs;
   private RevCommit currPsCommit;
 

gerrit-server/src/main/java/com/google/gerrit/server/change/EmailReviewComments.java

@@ -16,7 +16,7 @@ package com.google.gerrit.server.change;
 
 import static com.google.gerrit.server.CommentsUtil.COMMENT_ORDER;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -53,7 +53,7 @@ public class EmailReviewComments implements Runnable, RequestContext {
   interface Factory {
     EmailReviewComments create(
         NotifyHandling notify,
-        Multimap<RecipientType, Account.Id> accountsToNotify,
+        ListMultimap<RecipientType, Account.Id> accountsToNotify,
         ChangeNotes notes,
         PatchSet patchSet,
         IdentifiedUser user,
@@ -70,7 +70,7 @@ public class EmailReviewComments implements Runnable, RequestContext {
   private final ThreadLocalRequestContext requestContext;
 
   private final NotifyHandling notify;
-  private final Multimap<RecipientType, Account.Id> accountsToNotify;
+  private final ListMultimap<RecipientType, Account.Id> accountsToNotify;
   private final ChangeNotes notes;
   private final PatchSet patchSet;
   private final IdentifiedUser user;
@@ -88,7 +88,7 @@ public class EmailReviewComments implements Runnable, RequestContext {
       SchemaFactory<ReviewDb> schemaFactory,
       ThreadLocalRequestContext requestContext,
       @Assisted NotifyHandling notify,
-      @Assisted Multimap<RecipientType, Account.Id> accountsToNotify,
+      @Assisted ListMultimap<RecipientType, Account.Id> accountsToNotify,
       @Assisted ChangeNotes notes,
       @Assisted PatchSet patchSet,
       @Assisted IdentifiedUser user,

gerrit-server/src/main/java/com/google/gerrit/server/change/IncludedIn.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.server.change;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.extensions.config.ExternalIncludedIn;
 import com.google.gerrit.extensions.registration.DynamicSet;
@@ -81,10 +81,10 @@ class IncludedIn implements RestReadView<ChangeResource> {
       }
 
       IncludedInResolver.Result d = IncludedInResolver.resolve(r, rw, rev);
-      Multimap<String, String> external =
+      ListMultimap<String, String> external =
           MultimapBuilder.hashKeys().arrayListValues().build();
       for (ExternalIncludedIn ext : includedIn) {
-        Multimap<String, String> extIncludedIns = ext.getIncludedIn(
+        ListMultimap<String, String> extIncludedIns = ext.getIncludedIn(
             project.get(), rev.name(), d.getTags(), d.getBranches());
         if (extIncludedIns != null) {
           external.putAll(extIncludedIns);

gerrit-server/src/main/java/com/google/gerrit/server/change/IncludedInResolver.java

@@ -15,8 +15,8 @@
 package com.google.gerrit.server.change;
 
 import com.google.common.collect.LinkedListMultimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
@@ -76,7 +76,7 @@ public class IncludedInResolver {
   private final RevCommit target;
 
   private final RevFlag containsTarget;
-  private Multimap<RevCommit, String> commitToRef;
+  private ListMultimap<RevCommit, String> commitToRef;
   private List<RevCommit> tipsByCommitTime;
 
   private IncludedInResolver(Repository repo, RevWalk rw, RevCommit target,

gerrit-server/src/main/java/com/google/gerrit/server/change/NotifyUtil.java

@@ -18,7 +18,7 @@ import static java.util.stream.Collectors.joining;
 
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.NotifyInfo;
@@ -77,14 +77,14 @@ public class NotifyUtil {
     return notifyInfo.accounts == null || notifyInfo.accounts.isEmpty();
   }
 
-  public Multimap<RecipientType, Account.Id> resolveAccounts(
+  public ListMultimap<RecipientType, Account.Id> resolveAccounts(
       @Nullable Map<RecipientType, NotifyInfo> notifyDetails)
           throws OrmException, BadRequestException {
     if (isNullOrEmpty(notifyDetails)) {
       return ImmutableListMultimap.of();
     }
 
-    Multimap<RecipientType, Account.Id> m = null;
+    ListMultimap<RecipientType, Account.Id> m = null;
     for (Entry<RecipientType, NotifyInfo> e : notifyDetails.entrySet()) {
       List<String> accounts = e.getValue().accounts;
       if (accounts != null) {

gerrit-server/src/main/java/com/google/gerrit/server/change/PatchSetInserter.java

@@ -20,7 +20,7 @@ import static com.google.gerrit.server.notedb.ReviewerStateInternal.CC;
 import static com.google.gerrit.server.notedb.ReviewerStateInternal.REVIEWER;
 
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
 import com.google.gerrit.extensions.restapi.AuthException;
@@ -100,7 +100,7 @@ public class PatchSetInserter extends BatchUpdate.Op {
   private List<String> groups = Collections.emptyList();
   private boolean fireRevisionCreated = true;
   private NotifyHandling notify = NotifyHandling.ALL;
-  private Multimap<RecipientType, Account.Id> accountsToNotify =
+  private ListMultimap<RecipientType, Account.Id> accountsToNotify =
       ImmutableListMultimap.of();
   private boolean allowClosed;
   private boolean copyApprovals = true;
@@ -185,7 +185,7 @@ public class PatchSetInserter extends BatchUpdate.Op {
   }
 
   public PatchSetInserter setAccountsToNotify(
-      Multimap<RecipientType, Account.Id> accountsToNotify) {
+      ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     this.accountsToNotify = checkNotNull(accountsToNotify);
     return this;
   }

gerrit-server/src/main/java/com/google/gerrit/server/change/PostReview.java

@@ -27,9 +27,9 @@ import com.google.auto.value.AutoValue;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.Ordering;
 import com.google.common.hash.HashCode;
 import com.google.common.hash.Hashing;
@@ -207,7 +207,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
       input.notify = NotifyHandling.NONE;
     }
 
-    Multimap<RecipientType, Account.Id> accountsToNotify =
+    ListMultimap<RecipientType, Account.Id> accountsToNotify =
         notifyUtil.resolveAccounts(input.notifyDetails);
 
     Map<String, AddReviewerResult> reviewerJsonResults = null;
@@ -304,7 +304,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
 
   private void emailReviewers(Change change,
       List<PostReviewers.Addition> reviewerAdditions, NotifyHandling notify,
-      Multimap<RecipientType, Account.Id> accountsToNotify) {
+      ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     List<Account.Id> to = new ArrayList<>();
     List<Account.Id> cc = new ArrayList<>();
     for (PostReviewers.Addition addition : reviewerAdditions) {
@@ -671,7 +671,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
   private class Op extends BatchUpdate.Op {
     private final PatchSet.Id psId;
     private final ReviewInput in;
-    private final Multimap<RecipientType, Account.Id> accountsToNotify;
+    private final ListMultimap<RecipientType, Account.Id> accountsToNotify;
     private final List<PostReviewers.Addition> reviewerResults;
 
     private IdentifiedUser user;
@@ -684,7 +684,7 @@ public class PostReview implements RestModifyView<RevisionResource, ReviewInput>
     private Map<String, Short> oldApprovals = new HashMap<>();
 
     private Op(PatchSet.Id psId, ReviewInput in,
-        Multimap<RecipientType, Account.Id> accountsToNotify,
+        ListMultimap<RecipientType, Account.Id> accountsToNotify,
         List<PostReviewers.Addition> reviewerResults) {
       this.psId = psId;
       this.in = in;

gerrit-server/src/main/java/com/google/gerrit/server/change/PostReviewers.java

@@ -21,8 +21,8 @@ import static com.google.gerrit.extensions.client.ReviewerState.REVIEWER;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.common.data.GroupDescription;
 import com.google.gerrit.common.errors.NoSuchGroupException;
@@ -201,7 +201,7 @@ public class PostReviewers
 
   private Addition putAccount(String reviewer, ReviewerResource rsrc,
       ReviewerState state, NotifyHandling notify,
-      Multimap<RecipientType, Account.Id> accountsToNotify)
+      ListMultimap<RecipientType, Account.Id> accountsToNotify)
           throws UnprocessableEntityException {
     Account member = rsrc.getReviewerUser().getAccount();
     ChangeControl control = rsrc.getReviewerControl();
@@ -303,7 +303,7 @@ public class PostReviewers
     protected Addition(String reviewer, ChangeResource rsrc,
         Map<Account.Id, ChangeControl> reviewers, ReviewerState state,
         NotifyHandling notify,
-        Multimap<RecipientType, Account.Id> accountsToNotify) {
+        ListMultimap<RecipientType, Account.Id> accountsToNotify) {
       result = new AddReviewerResult(reviewer);
       if (reviewers == null) {
         this.reviewers = ImmutableMap.of();
@@ -342,7 +342,7 @@ public class PostReviewers
     final Map<Account.Id, ChangeControl> reviewers;
     final ReviewerState state;
     final NotifyHandling notify;
-    final Multimap<RecipientType, Account.Id> accountsToNotify;
+    final ListMultimap<RecipientType, Account.Id> accountsToNotify;
     List<PatchSetApproval> addedReviewers;
     Collection<Account.Id> addedCCs;
 
@@ -351,7 +351,7 @@ public class PostReviewers
 
     Op(ChangeResource rsrc, Map<Account.Id, ChangeControl> reviewers,
         ReviewerState state, NotifyHandling notify,
-        Multimap<RecipientType, Account.Id> accountsToNotify) {
+        ListMultimap<RecipientType, Account.Id> accountsToNotify) {
       this.rsrc = rsrc;
       this.reviewers = reviewers;
       this.state = state;
@@ -407,7 +407,7 @@ public class PostReviewers
 
   public void emailReviewers(Change change, Collection<Account.Id> added,
       Collection<Account.Id> copied, NotifyHandling notify,
-      Multimap<RecipientType, Account.Id> accountsToNotify) {
+      ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     if (added.isEmpty() && copied.isEmpty()) {
       return;
     }

gerrit-server/src/main/java/com/google/gerrit/server/change/Submit.java

@@ -21,7 +21,7 @@ import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.data.ParameterizedString;
 import com.google.gerrit.extensions.api.changes.SubmitInput;
@@ -418,7 +418,7 @@ public class Submit implements RestModifyView<RevisionResource, SubmitInput>,
       mergeabilityMap.add(change);
     }
 
-    Multimap<Branch.NameKey, ChangeData> cbb = cs.changesByBranch();
+    ListMultimap<Branch.NameKey, ChangeData> cbb = cs.changesByBranch();
     for (Branch.NameKey branch : cbb.keySet()) {
       Collection<ChangeData> targetBranch = cbb.get(branch);
       HashMap<Change.Id, RevCommit> commits =

gerrit-server/src/main/java/com/google/gerrit/server/change/WalkSorter.java

@@ -20,7 +20,7 @@ import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Ordering;
 import com.google.gerrit.reviewdb.client.PatchSet;
@@ -105,7 +105,7 @@ class WalkSorter {
 
   public Iterable<PatchSetData> sort(Iterable<ChangeData> in)
       throws OrmException, IOException {
-    Multimap<Project.NameKey, ChangeData> byProject =
+    ListMultimap<Project.NameKey, ChangeData> byProject =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (ChangeData cd : in) {
       byProject.put(cd.change().getProject(), cd);
@@ -126,7 +126,7 @@ class WalkSorter {
     try (Repository repo = repoManager.openRepository(project);
         RevWalk rw = new RevWalk(repo)) {
       rw.setRetainBody(retainBody);
-      Multimap<RevCommit, PatchSetData> byCommit = byCommit(rw, in);
+      ListMultimap<RevCommit, PatchSetData> byCommit = byCommit(rw, in);
       if (byCommit.isEmpty()) {
         return ImmutableList.of();
       } else if (byCommit.size() == 1) {
@@ -151,8 +151,8 @@ class WalkSorter {
       // the input size is small enough that this is not an issue.)
 
       Set<RevCommit> commits = byCommit.keySet();
-      Multimap<RevCommit, RevCommit> children = collectChildren(commits);
+      ListMultimap<RevCommit, RevCommit> children = collectChildren(commits);
-      Multimap<RevCommit, RevCommit> pending =
+      ListMultimap<RevCommit, RevCommit> pending =
           MultimapBuilder.hashKeys().arrayListValues().build();
       Deque<RevCommit> todo = new ArrayDeque<>();
 
@@ -195,9 +195,9 @@ class WalkSorter {
     }
   }
 
-  private static Multimap<RevCommit, RevCommit> collectChildren(
+  private static ListMultimap<RevCommit, RevCommit> collectChildren(
       Set<RevCommit> commits) {
-    Multimap<RevCommit, RevCommit> children =
+    ListMultimap<RevCommit, RevCommit> children =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (RevCommit c : commits) {
       for (RevCommit p : c.getParents()) {
@@ -209,8 +209,9 @@ class WalkSorter {
     return children;
   }
 
-  private static int emit(RevCommit c, Multimap<RevCommit, PatchSetData> byCommit,
+  private static int emit(RevCommit c,
-      List<PatchSetData> result, RevFlag done) {
+      ListMultimap<RevCommit, PatchSetData> byCommit, List<PatchSetData> result,
+      RevFlag done) {
     if (c.has(done)) {
       return 0;
     }
@@ -223,9 +224,9 @@ class WalkSorter {
     return 0;
   }
 
-  private Multimap<RevCommit, PatchSetData> byCommit(RevWalk rw,
+  private ListMultimap<RevCommit, PatchSetData> byCommit(RevWalk rw,
       Collection<ChangeData> in) throws OrmException, IOException {
-    Multimap<RevCommit, PatchSetData> byCommit =
+    ListMultimap<RevCommit, PatchSetData> byCommit =
         MultimapBuilder.hashKeys(in.size()).arrayListValues(1).build();
     for (ChangeData cd : in) {
       PatchSet maxPs = null;

gerrit-server/src/main/java/com/google/gerrit/server/config/TrackingFooters.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.server.config;
 
 import com.google.common.collect.ArrayListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 
 import org.eclipse.jgit.revwalk.FooterLine;
 
@@ -37,8 +37,8 @@ public class TrackingFooters {
     return trackingFooters.isEmpty();
   }
 
-  public Multimap<String, String> extract(List<FooterLine> lines) {
+  public ListMultimap<String, String> extract(List<FooterLine> lines) {
-    Multimap<String, String> r = ArrayListMultimap.create();
+    ListMultimap<String, String> r = ArrayListMultimap.create();
     if (lines == null) {
       return r;
     }

gerrit-server/src/main/java/com/google/gerrit/server/edit/ChangeEditUtil.java

@@ -16,7 +16,7 @@ package com.google.gerrit.server.edit;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -171,7 +171,7 @@ public class ChangeEditUtil {
    * @throws RestApiException
    */
   public void publish(final ChangeEdit edit, NotifyHandling notify,
-      Multimap<RecipientType, Account.Id> accountsToNotify)
+      ListMultimap<RecipientType, Account.Id> accountsToNotify)
       throws IOException, OrmException, RestApiException, UpdateException {
     Change change = edit.getChange();
     try (Repository repo = gitManager.openRepository(change.getProject());

gerrit-server/src/main/java/com/google/gerrit/server/events/EventFactory.java

@@ -17,8 +17,8 @@ package com.google.gerrit.server.events;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static java.util.Comparator.comparing;
 
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.LabelType;
 import com.google.gerrit.common.data.LabelTypes;
@@ -354,7 +354,8 @@ public class EventFactory {
     return d;
   }
 
-  public void addTrackingIds(ChangeAttribute a, Multimap<String, String> set) {
+  public void addTrackingIds(ChangeAttribute a,
+      ListMultimap<String, String> set) {
     if (!set.isEmpty()) {
       a.trackingIds = new ArrayList<>(set.size());
       for (Map.Entry<String, Collection<String>> e : set.asMap().entrySet()) {

gerrit-server/src/main/java/com/google/gerrit/server/git/AbandonOp.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.server.git;
 
 import com.google.common.base.Strings;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -49,7 +49,7 @@ public class AbandonOp extends BatchUpdate.Op {
 
   private final String msgTxt;
   private final NotifyHandling notifyHandling;
-  private final Multimap<RecipientType, Account.Id> accountsToNotify;
+  private final ListMultimap<RecipientType, Account.Id> accountsToNotify;
   private final Account account;
 
   private Change change;
@@ -61,7 +61,7 @@ public class AbandonOp extends BatchUpdate.Op {
         @Assisted @Nullable Account account,
         @Assisted @Nullable String msgTxt,
         @Assisted NotifyHandling notifyHandling,
-        @Assisted Multimap<RecipientType, Account.Id> accountsToNotify);
+        @Assisted ListMultimap<RecipientType, Account.Id> accountsToNotify);
   }
 
   @AssistedInject
@@ -73,7 +73,7 @@ public class AbandonOp extends BatchUpdate.Op {
       @Assisted @Nullable Account account,
       @Assisted @Nullable String msgTxt,
       @Assisted NotifyHandling notifyHandling,
-      @Assisted Multimap<RecipientType, Account.Id> accountsToNotify) {
+      @Assisted ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     this.abandonedSenderFactory = abandonedSenderFactory;
     this.cmUtil = cmUtil;
     this.psUtil = psUtil;

gerrit-server/src/main/java/com/google/gerrit/server/git/ChangeSet.java

@@ -19,7 +19,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ListMultimap;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.reviewdb.client.Branch;
 import com.google.gerrit.reviewdb.client.Change;
@@ -82,7 +81,7 @@ public class ChangeSet {
     return changeData;
   }
 
-  public Multimap<Branch.NameKey, ChangeData> changesByBranch()
+  public ListMultimap<Branch.NameKey, ChangeData> changesByBranch()
       throws OrmException {
     ListMultimap<Branch.NameKey, ChangeData> ret =
         MultimapBuilder.hashKeys().arrayListValues().build();

gerrit-server/src/main/java/com/google/gerrit/server/git/EmailMerge.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.server.git;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -46,7 +46,7 @@ public class EmailMerge implements Runnable, RequestContext {
   public interface Factory {
     EmailMerge create(Project.NameKey project, Change.Id changeId,
         Account.Id submitter, NotifyHandling notifyHandling,
-        Multimap<RecipientType, Account.Id> accountsToNotify);
+        ListMultimap<RecipientType, Account.Id> accountsToNotify);
   }
 
   private final ExecutorService sendEmailsExecutor;
@@ -59,7 +59,7 @@ public class EmailMerge implements Runnable, RequestContext {
   private final Change.Id changeId;
   private final Account.Id submitter;
   private final NotifyHandling notifyHandling;
-  private final Multimap<RecipientType, Account.Id> accountsToNotify;
+  private final ListMultimap<RecipientType, Account.Id> accountsToNotify;
 
   private ReviewDb db;
 
@@ -73,7 +73,7 @@ public class EmailMerge implements Runnable, RequestContext {
       @Assisted Change.Id changeId,
       @Assisted @Nullable Account.Id submitter,
       @Assisted NotifyHandling notifyHandling,
-      @Assisted Multimap<RecipientType, Account.Id> accountsToNotify) {
+      @Assisted ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     this.sendEmailsExecutor = executor;
     this.mergedSenderFactory = mergedSenderFactory;
     this.schemaFactory = schemaFactory;

gerrit-server/src/main/java/com/google/gerrit/server/git/GroupCollector.java

@@ -22,7 +22,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Multimaps;
 import com.google.common.collect.SetMultimap;
@@ -103,16 +102,16 @@ public class GroupCollector {
     List<String> lookup(PatchSet.Id psId) throws OrmException;
   }
 
-  private final Multimap<ObjectId, PatchSet.Id> patchSetsBySha;
+  private final ListMultimap<ObjectId, PatchSet.Id> patchSetsBySha;
-  private final Multimap<ObjectId, String> groups;
+  private final ListMultimap<ObjectId, String> groups;
   private final SetMultimap<String, String> groupAliases;
   private final Lookup groupLookup;
 
   private boolean done;
 
-  public static GroupCollector create(Multimap<ObjectId, Ref> changeRefsById,
+  public static GroupCollector create(ListMultimap<ObjectId, Ref> changeRefsById,
-      final ReviewDb db, final PatchSetUtil psUtil,
+      ReviewDb db, PatchSetUtil psUtil, ChangeNotes.Factory notesFactory,
-      final ChangeNotes.Factory notesFactory, final Project.NameKey project) {
+      Project.NameKey project) {
     return new GroupCollector(
         transformRefs(changeRefsById),
         new Lookup() {
@@ -128,7 +127,7 @@ public class GroupCollector {
   }
 
   public static GroupCollector createForSchemaUpgradeOnly(
-      Multimap<ObjectId, Ref> changeRefsById, final ReviewDb db) {
+      ListMultimap<ObjectId, Ref> changeRefsById, ReviewDb db) {
     return new GroupCollector(
         transformRefs(changeRefsById),
         new Lookup() {
@@ -141,7 +140,7 @@ public class GroupCollector {
   }
 
   private GroupCollector(
-      Multimap<ObjectId, PatchSet.Id> patchSetsBySha,
+      ListMultimap<ObjectId, PatchSet.Id> patchSetsBySha,
       Lookup groupLookup) {
     this.patchSetsBySha = patchSetsBySha;
     this.groupLookup = groupLookup;
@@ -149,16 +148,16 @@ public class GroupCollector {
     groupAliases = MultimapBuilder.hashKeys().hashSetValues().build();
   }
 
-  private static Multimap<ObjectId, PatchSet.Id> transformRefs(
+  private static ListMultimap<ObjectId, PatchSet.Id> transformRefs(
-      Multimap<ObjectId, Ref> refs) {
+      ListMultimap<ObjectId, Ref> refs) {
     return Multimaps.transformValues(
         refs, r -> PatchSet.Id.fromRef(r.getName()));
   }
 
   @VisibleForTesting
   GroupCollector(
-      Multimap<ObjectId, PatchSet.Id> patchSetsBySha,
+      ListMultimap<ObjectId, PatchSet.Id> patchSetsBySha,
-      final ListMultimap<PatchSet.Id, String> groupLookup) {
+      ListMultimap<PatchSet.Id, String> groupLookup) {
     this(
         patchSetsBySha,
         new Lookup() {

gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java

@@ -21,12 +21,13 @@ import static java.util.Comparator.comparing;
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSetMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
+import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.TimeUtil;
@@ -109,7 +110,7 @@ public class MergeOp implements AutoCloseable {
     private final ImmutableMap<Change.Id, ChangeData> changes;
     private final ImmutableSetMultimap<Branch.NameKey, Change.Id> byBranch;
     private final Map<Change.Id, CodeReviewCommit> commits;
-    private final Multimap<Change.Id, String> problems;
+    private final ListMultimap<Change.Id, String> problems;
 
     private CommitStatus(ChangeSet cs) throws OrmException {
       checkArgument(!cs.furtherHiddenChanges(),
@@ -163,8 +164,8 @@ public class MergeOp implements AutoCloseable {
       return problems.isEmpty();
     }
 
-    public ImmutableMultimap<Change.Id, String> getProblems() {
+    public ImmutableListMultimap<Change.Id, String> getProblems() {
-      return ImmutableMultimap.copyOf(problems);
+      return ImmutableListMultimap.copyOf(problems);
     }
 
     public List<SubmitRecord> getSubmitRecords(Change.Id id) {
@@ -228,7 +229,7 @@ public class MergeOp implements AutoCloseable {
   private CommitStatus commits;
   private ReviewDb db;
   private SubmitInput submitInput;
-  private Multimap<RecipientType, Account.Id> accountsToNotify;
+  private ListMultimap<RecipientType, Account.Id> accountsToNotify;
   private Set<Project.NameKey> allProjects;
   private boolean dryrun;
 
@@ -452,7 +453,7 @@ public class MergeOp implements AutoCloseable {
     logDebug("Beginning merge attempt on {}", cs);
     Map<Branch.NameKey, BranchBatch> toSubmit = new HashMap<>();
 
-    Multimap<Branch.NameKey, ChangeData> cbb;
+    ListMultimap<Branch.NameKey, ChangeData> cbb;
     try {
       cbb = cs.changesByBranch();
     } catch (OrmException e) {
@@ -596,7 +597,7 @@ public class MergeOp implements AutoCloseable {
       Collection<ChangeData> submitted) throws IntegrationException {
     logDebug("Validating {} changes", submitted.size());
     List<ChangeData> toSubmit = new ArrayList<>(submitted.size());
-    Multimap<ObjectId, PatchSet.Id> revisions = getRevisions(or, submitted);
+    SetMultimap<ObjectId, PatchSet.Id> revisions = getRevisions(or, submitted);
 
     SubmitType submitType = null;
     ChangeData choseSubmitTypeFrom = null;
@@ -696,7 +697,7 @@ public class MergeOp implements AutoCloseable {
     return new AutoValue_MergeOp_BranchBatch(submitType, toSubmit);
   }
 
-  private Multimap<ObjectId, PatchSet.Id> getRevisions(OpenRepo or,
+  private SetMultimap<ObjectId, PatchSet.Id> getRevisions(OpenRepo or,
       Collection<ChangeData> cds) throws IntegrationException {
     try {
       List<String> refNames = new ArrayList<>(cds.size());
@@ -706,7 +707,7 @@ public class MergeOp implements AutoCloseable {
           refNames.add(c.currentPatchSetId().toRefName());
         }
       }
-      Multimap<ObjectId, PatchSet.Id> revisions =
+      SetMultimap<ObjectId, PatchSet.Id> revisions =
           MultimapBuilder.hashKeys(cds.size()).hashSetValues(1).build();
       for (Map.Entry<String, Ref> e : or.repo.getRefDatabase().exactRef(
           refNames.toArray(new String[refNames.size()])).entrySet()) {

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java

@@ -44,9 +44,7 @@ import com.google.common.collect.LinkedListMultimap;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
-import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 import com.google.common.collect.SortedSetMultimap;
 import com.google.gerrit.common.Nullable;
@@ -325,7 +323,7 @@ public class ReceiveCommits {
   private final Set<ObjectId> validCommits = new HashSet<>();
 
   private ListMultimap<Change.Id, Ref> refsByChange;
-  private SetMultimap<ObjectId, Ref> refsById;
+  private ListMultimap<ObjectId, Ref> refsById;
   private Map<String, Ref> allRefs;
 
   private final SubmoduleOp.Factory subOpFactory;
@@ -1325,8 +1323,8 @@ public class ReceiveCommits {
       return new MailRecipients(reviewer, cc);
     }
 
-    Multimap<RecipientType, Account.Id> getAccountsToNotify() {
+    ListMultimap<RecipientType, Account.Id> getAccountsToNotify() {
-      Multimap<RecipientType, Account.Id> accountsToNotify =
+      ListMultimap<RecipientType, Account.Id> accountsToNotify =
           MultimapBuilder.hashKeys().arrayListValues().build();
       accountsToNotify.putAll(RecipientType.TO, tos);
       accountsToNotify.putAll(RecipientType.CC, ccs);
@@ -1673,8 +1671,9 @@ public class ReceiveCommits {
     logDebug("Finding new and replaced changes");
     newChanges = new ArrayList<>();
 
-    SetMultimap<ObjectId, Ref> existing = changeRefsById();
+    ListMultimap<ObjectId, Ref> existing = changeRefsById();
-    GroupCollector groupCollector = GroupCollector.create(changeRefsById(), db, psUtil,
+    GroupCollector groupCollector = GroupCollector.create(
+        changeRefsById(), db, psUtil,
         notesFactory, project.getNameKey());
 
     try {
@@ -2527,7 +2526,7 @@ public class ReceiveCommits {
   private void initChangeRefMaps() {
     if (refsByChange == null) {
       int estRefsPerChange = 4;
-      refsById = MultimapBuilder.hashKeys().hashSetValues().build();
+      refsById = MultimapBuilder.hashKeys().arrayListValues().build();
       refsByChange =
           MultimapBuilder.hashKeys(allRefs.size() / estRefsPerChange)
               .arrayListValues(estRefsPerChange)
@@ -2550,7 +2549,7 @@ public class ReceiveCommits {
     return refsByChange;
   }
 
-  private SetMultimap<ObjectId, Ref> changeRefsById() {
+  private ListMultimap<ObjectId, Ref> changeRefsById() {
     initChangeRefMaps();
     return refsById;
   }
@@ -2630,7 +2629,7 @@ public class ReceiveCommits {
       if (!(parsedObject instanceof RevCommit)) {
         return;
       }
-      SetMultimap<ObjectId, Ref> existing = changeRefsById();
+      ListMultimap<ObjectId, Ref> existing = changeRefsById();
       walk.markStart((RevCommit)parsedObject);
       markHeadsAsUninteresting(walk, cmd.getRefName());
       int i = 0;
@@ -2727,7 +2726,7 @@ public class ReceiveCommits {
         rw.markUninteresting(rw.parseCommit(cmd.getOldId()));
       }
 
-      SetMultimap<ObjectId, Ref> byCommit = changeRefsById();
+      ListMultimap<ObjectId, Ref> byCommit = changeRefsById();
       Map<Change.Key, ChangeNotes> byKey = null;
       List<ReplaceRequest> replaceAndClose = new ArrayList<>();
 

gerrit-server/src/main/java/com/google/gerrit/server/git/SubmoduleOp.java

@@ -15,7 +15,6 @@
 package com.google.gerrit.server.git;
 
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.SetMultimap;
 import com.google.gerrit.common.data.SubscribeSection;
@@ -115,7 +114,7 @@ public class SubmoduleOp {
   // sorted version of affectedBranches
   private final ImmutableSet<Branch.NameKey> sortedBranches;
   // map of superproject branch and its submodule subscriptions
-  private final Multimap<Branch.NameKey, SubmoduleSubscription> targets;
+  private final SetMultimap<Branch.NameKey, SubmoduleSubscription> targets;
   // map of superproject and its branches which has submodule subscriptions
   private final SetMultimap<Project.NameKey, Branch.NameKey> branchesByProject;
 

gerrit-server/src/main/java/com/google/gerrit/server/git/strategy/SubmitStrategy.java

@@ -16,7 +16,7 @@ package com.google.gerrit.server.git.strategy;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Sets;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -99,7 +99,7 @@ public abstract class SubmitStrategy {
           Set<RevCommit> alreadyAccepted,
           RequestId submissionId,
           NotifyHandling notifyHandling,
-          Multimap<RecipientType, Account.Id> accountsToNotify,
+          ListMultimap<RecipientType, Account.Id> accountsToNotify,
           SubmoduleOp submoduleOp,
           boolean dryrun);
     }
@@ -133,7 +133,7 @@ public abstract class SubmitStrategy {
     final RequestId submissionId;
     final SubmitType submitType;
     final NotifyHandling notifyHandling;
-    final Multimap<RecipientType, Account.Id> accountsToNotify;
+    final ListMultimap<RecipientType, Account.Id> accountsToNotify;
     final SubmoduleOp submoduleOp;
 
     final ProjectState project;
@@ -172,7 +172,7 @@ public abstract class SubmitStrategy {
         @Assisted RequestId submissionId,
         @Assisted SubmitType submitType,
         @Assisted NotifyHandling notifyHandling,
-        @Assisted Multimap<RecipientType, Account.Id> accountsToNotify,
+        @Assisted ListMultimap<RecipientType, Account.Id> accountsToNotify,
         @Assisted SubmoduleOp submoduleOp,
         @Assisted boolean dryrun) {
       this.accountCache = accountCache;

gerrit-server/src/main/java/com/google/gerrit/server/git/strategy/SubmitStrategyFactory.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.server.git.strategy;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
 import com.google.gerrit.extensions.client.SubmitType;
@@ -59,7 +59,7 @@ public class SubmitStrategyFactory {
       Branch.NameKey destBranch, IdentifiedUser caller, MergeTip mergeTip,
       CommitStatus commits, RequestId submissionId,
       NotifyHandling notifyHandling,
-      Multimap<RecipientType, Account.Id> accountsToNotify,
+      ListMultimap<RecipientType, Account.Id> accountsToNotify,
       SubmoduleOp submoduleOp, boolean dryrun) throws IntegrationException {
     SubmitStrategy.Arguments args = argsFactory.create(submitType, destBranch,
         commits, rw, caller, mergeTip, inserter, repo, canMergeFlag, db,

gerrit-server/src/main/java/com/google/gerrit/server/group/GroupsCollection.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.server.group;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.data.GroupDescription;
 import com.google.gerrit.common.data.GroupDescriptions;
 import com.google.gerrit.common.data.GroupReference;
@@ -70,7 +70,7 @@ public class GroupsCollection implements
   }
 
   @Override
-  public void setParams(Multimap<String, String> params)
+  public void setParams(ListMultimap<String, String> params)
       throws BadRequestException {
     if (params.containsKey("query") && params.containsKey("query2")) {
       throw new BadRequestException(

gerrit-server/src/main/java/com/google/gerrit/server/index/change/AllChangesIndexer.java

@@ -23,8 +23,8 @@ import static org.eclipse.jgit.lib.RefDatabase.ALL;
 import com.google.common.base.Stopwatch;
 import com.google.common.collect.ComparisonChain;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Sets;
 import com.google.common.util.concurrent.ListenableFuture;
@@ -217,7 +217,7 @@ public class AllChangesIndexer
     return new Callable<Void>() {
       @Override
       public Void call() throws Exception {
-        Multimap<ObjectId, ChangeData> byId =
+        ListMultimap<ObjectId, ChangeData> byId =
             MultimapBuilder.hashKeys().arrayListValues().build();
         // TODO(dborowitz): Opening all repositories in a live server may be
         // wasteful; see if we can determine which ones it is safe to close
@@ -260,7 +260,7 @@ public class AllChangesIndexer
     private final ChangeIndexer indexer;
     private final ThreeWayMergeStrategy mergeStrategy;
     private final AutoMerger autoMerger;
-    private final Multimap<ObjectId, ChangeData> byId;
+    private final ListMultimap<ObjectId, ChangeData> byId;
     private final ProgressMonitor done;
     private final ProgressMonitor failed;
     private final PrintWriter verboseWriter;
@@ -269,7 +269,7 @@ public class AllChangesIndexer
     private ProjectIndexer(ChangeIndexer indexer,
         ThreeWayMergeStrategy mergeStrategy,
         AutoMerger autoMerger,
-        Multimap<ObjectId, ChangeData> changesByCommitId,
+        ListMultimap<ObjectId, ChangeData> changesByCommitId,
         Repository repo,
         ProgressMonitor done,
         ProgressMonitor failed,

gerrit-server/src/main/java/com/google/gerrit/server/index/change/StalenessChecker.java

@@ -24,7 +24,6 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ListMultimap;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
@@ -110,7 +109,7 @@ public class StalenessChecker {
       Change indexChange,
       @Nullable Change reviewDbChange,
       SetMultimap<Project.NameKey, RefState> states,
-      Multimap<Project.NameKey, RefStatePattern> patterns) {
+      ListMultimap<Project.NameKey, RefStatePattern> patterns) {
     return reviewDbChangeIsStale(indexChange, reviewDbChange)
         || refsAreStale(repoManager, id, states, patterns);
   }
@@ -119,7 +118,7 @@ public class StalenessChecker {
   static boolean refsAreStale(GitRepositoryManager repoManager,
       Change.Id id,
       SetMultimap<Project.NameKey, RefState> states,
-      Multimap<Project.NameKey, RefStatePattern> patterns) {
+      ListMultimap<Project.NameKey, RefStatePattern> patterns) {
     Set<Project.NameKey> projects =
         Sets.union(states.keySet(), patterns.keySet());
 
@@ -172,7 +171,7 @@ public class StalenessChecker {
     return result;
   }
 
-  private Multimap<Project.NameKey, RefStatePattern> parsePatterns(
+  private ListMultimap<Project.NameKey, RefStatePattern> parsePatterns(
       ChangeData cd) {
     return parsePatterns(cd.getRefStatePatterns());
   }
@@ -197,7 +196,7 @@ public class StalenessChecker {
   private static boolean refsAreStale(GitRepositoryManager repoManager,
       Change.Id id, Project.NameKey project,
       SetMultimap<Project.NameKey, RefState> allStates,
-      Multimap<Project.NameKey, RefStatePattern> allPatterns) {
+      ListMultimap<Project.NameKey, RefStatePattern> allPatterns) {
     try (Repository repo = repoManager.openRepository(project)) {
       Set<RefState> states = allStates.get(project);
       for (RefState state : states) {

gerrit-server/src/main/java/com/google/gerrit/server/mail/send/ChangeEmail.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.server.mail.send;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.errors.EmailException;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -310,7 +310,7 @@ public abstract class ChangeEmail extends NotificationEmail {
       // BCC anyone who has starred this change
       // and remove anyone who has ignored this change.
       //
-      Multimap<Account.Id, String> stars =
+      ListMultimap<Account.Id, String> stars =
           args.starredChangesUtil.byChangeFromIndex(change.getId());
       for (Map.Entry<Account.Id, Collection<String>> e :
           stars.asMap().entrySet()) {

gerrit-server/src/main/java/com/google/gerrit/server/mail/send/OutgoingEmail.java

@@ -20,7 +20,7 @@ import static com.google.gerrit.extensions.client.GeneralPreferencesInfo.EmailSt
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.errors.EmailException;
 import com.google.gerrit.extensions.api.changes.NotifyHandling;
 import com.google.gerrit.extensions.api.changes.RecipientType;
@@ -76,7 +76,7 @@ public abstract class OutgoingEmail {
   private Address smtpFromAddress;
   private StringBuilder textBody;
   private StringBuilder htmlBody;
-  private Multimap<RecipientType, Account.Id> accountsToNotify =
+  private ListMultimap<RecipientType, Account.Id> accountsToNotify =
       ImmutableListMultimap.of();
   protected VelocityContext velocityContext;
   protected Map<String, Object> soyContext;
@@ -101,7 +101,7 @@ public abstract class OutgoingEmail {
   }
 
   public void setAccountsToNotify(
-      Multimap<RecipientType, Account.Id> accountsToNotify) {
+      ListMultimap<RecipientType, Account.Id> accountsToNotify) {
     this.accountsToNotify = checkNotNull(accountsToNotify);
   }
 

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeBundle.java

@@ -37,9 +37,9 @@ import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSortedMap;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.LinkedListMultimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.Ordering;
 import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
@@ -562,7 +562,7 @@ public class ChangeBundle {
     // but easy to reason about.
     List<ChangeMessage> as = new LinkedList<>(bundleA.filterChangeMessages());
 
-    Multimap<ChangeMessageCandidate, ChangeMessage> bs =
+    ListMultimap<ChangeMessageCandidate, ChangeMessage> bs =
         LinkedListMultimap.create();
     for (ChangeMessage b : bundleB.filterChangeMessages()) {
       bs.put(ChangeMessageCandidate.create(b), b);

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNoteUtil.java

@@ -21,7 +21,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.primitives.Ints;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
@@ -525,7 +525,7 @@ public class ChangeNoteUtil {
    *     side.
    * @param out output stream to write to.
    */
-  void buildNote(Multimap<Integer, Comment> comments,
+  void buildNote(ListMultimap<Integer, Comment> comments,
       OutputStream out) {
     if (comments.isEmpty()) {
       return;

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNotesParser.java

@@ -40,8 +40,8 @@ import com.google.common.base.Splitter;
 import com.google.common.collect.HashBasedTable;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.LinkedListMultimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Sets;
 import com.google.common.collect.Table;
@@ -130,7 +130,7 @@ class ChangeNotesParser {
   private final List<Account.Id> allPastReviewers;
   private final List<ReviewerStatusUpdate> reviewerUpdates;
   private final List<SubmitRecord> submitRecords;
-  private final Multimap<RevId, Comment> comments;
+  private final ListMultimap<RevId, Comment> comments;
   private final Map<PatchSet.Id, PatchSet> patchSets;
   private final Set<PatchSet.Id> deletedPatchSets;
   private final Map<PatchSet.Id, PatchSetState> patchSetStates;
@@ -138,7 +138,8 @@ class ChangeNotesParser {
   private final Map<ApprovalKey, PatchSetApproval> approvals;
   private final List<PatchSetApproval> bufferedApprovals;
   private final List<ChangeMessage> allChangeMessages;
-  private final Multimap<PatchSet.Id, ChangeMessage> changeMessagesByPatchSet;
+  private final ListMultimap<PatchSet.Id, ChangeMessage>
+      changeMessagesByPatchSet;
 
   // Non-final private members filled in during the parsing process.
   private String branch;
@@ -248,8 +249,8 @@ class ChangeNotesParser {
     return null;
   }
 
-  private Multimap<PatchSet.Id, PatchSetApproval> buildApprovals() {
+  private ListMultimap<PatchSet.Id, PatchSetApproval> buildApprovals() {
-    Multimap<PatchSet.Id, PatchSetApproval> result =
+    ListMultimap<PatchSet.Id, PatchSetApproval> result =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (PatchSetApproval a : approvals.values()) {
       if (!patchSets.containsKey(a.getPatchSetId())) {
@@ -283,7 +284,7 @@ class ChangeNotesParser {
     return Lists.reverse(allChangeMessages);
   }
 
-  private Multimap<PatchSet.Id, ChangeMessage> buildMessagesByPatchSet() {
+  private ListMultimap<PatchSet.Id, ChangeMessage> buildMessagesByPatchSet() {
     for (Collection<ChangeMessage> v :
         changeMessagesByPatchSet.asMap().values()) {
       Collections.reverse((List<ChangeMessage>) v);

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNotesState.java

@@ -22,7 +22,7 @@ import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.SubmitRecord;
 import com.google.gerrit.reviewdb.client.Account;
@@ -95,14 +95,14 @@ public abstract class ChangeNotesState {
       @Nullable Set<Account.Id> pastAssignees,
       @Nullable Set<String> hashtags,
       Map<PatchSet.Id, PatchSet> patchSets,
-      Multimap<PatchSet.Id, PatchSetApproval> approvals,
+      ListMultimap<PatchSet.Id, PatchSetApproval> approvals,
       ReviewerSet reviewers,
       List<Account.Id> allPastReviewers,
       List<ReviewerStatusUpdate> reviewerUpdates,
       List<SubmitRecord> submitRecords,
       List<ChangeMessage> allChangeMessages,
-      Multimap<PatchSet.Id, ChangeMessage> changeMessagesByPatchSet,
+      ListMultimap<PatchSet.Id, ChangeMessage> changeMessagesByPatchSet,
-      Multimap<RevId, Comment> publishedComments) {
+      ListMultimap<RevId, Comment> publishedComments) {
     if (hashtags == null) {
       hashtags = ImmutableSet.of();
     }

gerrit-server/src/main/java/com/google/gerrit/server/notedb/DraftCommentNotes.java

@@ -21,7 +21,7 @@ import static com.google.gerrit.server.notedb.NoteDbTable.CHANGES;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.metrics.Timer1;
@@ -167,7 +167,7 @@ public class DraftCommentNotes extends AbstractChangeNotes<DraftCommentNotes> {
     revisionNoteMap = RevisionNoteMap.parse(
         args.noteUtil, getChangeId(), reader, NoteMap.read(reader, tipCommit),
         PatchLineComment.Status.DRAFT);
-    Multimap<RevId, Comment> cs =
+    ListMultimap<RevId, Comment> cs =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (ChangeRevisionNote rn : revisionNoteMap.revisionNotes.values()) {
       for (Comment c : rn.getComments()) {

gerrit-server/src/main/java/com/google/gerrit/server/notedb/RevisionNoteBuilder.java

@@ -18,8 +18,8 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.gerrit.server.CommentsUtil.COMMENT_ORDER;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.reviewdb.client.Comment;
 import com.google.gerrit.reviewdb.client.RevId;
@@ -112,8 +112,8 @@ class RevisionNoteBuilder {
     this.pushCert = pushCert;
   }
 
-  private Multimap<Integer, Comment> buildCommentMap() {
+  private ListMultimap<Integer, Comment> buildCommentMap() {
-    Multimap<Integer, Comment> all =
+    ListMultimap<Integer, Comment> all =
         MultimapBuilder.hashKeys().arrayListValues().build();
 
     for (Comment c : baseComments) {
@@ -131,7 +131,7 @@ class RevisionNoteBuilder {
 
   private void buildNoteJson(ChangeNoteUtil noteUtil, OutputStream out)
       throws IOException {
-    Multimap<Integer, Comment> comments = buildCommentMap();
+    ListMultimap<Integer, Comment> comments = buildCommentMap();
     if (comments.isEmpty() && pushCert == null) {
       return;
     }

gerrit-server/src/main/java/com/google/gerrit/server/notedb/RobotCommentNotes.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.server.notedb;
 
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.reviewdb.client.Change;
@@ -95,7 +95,7 @@ public class RobotCommentNotes extends AbstractChangeNotes<RobotCommentNotes> {
     ObjectReader reader = handle.walk().getObjectReader();
     revisionNoteMap = RevisionNoteMap.parseRobotComments(args.noteUtil, reader,
         NoteMap.read(reader, tipCommit));
-    Multimap<RevId, RobotComment> cs =
+    ListMultimap<RevId, RobotComment> cs =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (RobotCommentsRevisionNote rn :
         revisionNoteMap.revisionNotes.values()) {

gerrit-server/src/main/java/com/google/gerrit/server/notedb/rebuild/ChangeRebuilderImpl.java

@@ -25,9 +25,9 @@ import static java.util.stream.Collectors.toList;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Ordering;
 import com.google.common.collect.Sets;
@@ -299,7 +299,7 @@ public class ChangeRebuilderImpl extends ChangeRebuilder {
     // We will rebuild all events, except for draft comments, in buckets based
     // on author and timestamp.
     List<Event> events = new ArrayList<>();
-    Multimap<Account.Id, DraftCommentEvent> draftCommentEvents =
+    ListMultimap<Account.Id, DraftCommentEvent> draftCommentEvents =
         MultimapBuilder.hashKeys().arrayListValues().build();
 
     events.addAll(getHashtagsEvents(change, manager));

gerrit-server/src/main/java/com/google/gerrit/server/plugins/AutoRegisterModules.java

@@ -19,7 +19,7 @@ import static com.google.gerrit.server.plugins.AutoRegisterUtil.calculateBindAnn
 import static com.google.gerrit.server.plugins.PluginGuiceEnvironment.is;
 
 import com.google.common.collect.LinkedListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.annotations.Export;
 import com.google.gerrit.extensions.annotations.ExtensionPoint;
 import com.google.gerrit.extensions.annotations.Listen;
@@ -54,7 +54,7 @@ class AutoRegisterModules {
   private final ModuleGenerator httpGen;
 
   private Set<Class<?>> sysSingletons;
-  private Multimap<TypeLiteral<?>, Class<?>> sysListen;
+  private ListMultimap<TypeLiteral<?>, Class<?>> sysListen;
   private String initJs;
 
   Module sysModule;

gerrit-server/src/main/java/com/google/gerrit/server/plugins/JarScanner.java

@@ -19,9 +19,9 @@ import static com.google.common.collect.Iterables.transform;
 
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 
 import org.eclipse.jgit.util.IO;
@@ -67,7 +67,7 @@ public class JarScanner implements PluginContentScanner, AutoCloseable {
       String pluginName, Iterable<Class<? extends Annotation>> annotations)
       throws InvalidPluginException {
     Set<String> descriptors = new HashSet<>();
-    Multimap<String, JarScanner.ClassData> rawMap =
+    ListMultimap<String, JarScanner.ClassData> rawMap =
         MultimapBuilder.hashKeys().arrayListValues().build();
     Map<Class<? extends Annotation>, String> classObjToClassDescr =
         new HashMap<>();

gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginLoader.java

@@ -24,8 +24,8 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.Ordering;
+import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 import com.google.common.io.ByteStreams;
 import com.google.gerrit.extensions.annotations.PluginName;
@@ -399,7 +399,7 @@ public class PluginLoader implements LifecycleListener {
   }
 
   public synchronized void rescan() {
-    Multimap<String, Path> pluginsFiles = prunePlugins(pluginsDir);
+    SetMultimap<String, Path> pluginsFiles = prunePlugins(pluginsDir);
     if (pluginsFiles.isEmpty()) {
       return;
     }
@@ -478,7 +478,7 @@ public class PluginLoader implements LifecycleListener {
     return sortedPlugins;
   }
 
-  private void syncDisabledPlugins(Multimap<String, Path> jars) {
+  private void syncDisabledPlugins(SetMultimap<String, Path> jars) {
     stopRemovedPlugins(jars);
     dropRemovedDisabledPlugins(jars);
   }
@@ -525,7 +525,7 @@ public class PluginLoader implements LifecycleListener {
     }
   }
 
-  private void stopRemovedPlugins(Multimap<String, Path> jars) {
+  private void stopRemovedPlugins(SetMultimap<String, Path> jars) {
     Set<String> unload = Sets.newHashSet(running.keySet());
     for (Map.Entry<String, Collection<Path>> entry : jars.asMap().entrySet()) {
       for (Path path : entry.getValue()) {
@@ -539,7 +539,7 @@ public class PluginLoader implements LifecycleListener {
     }
   }
 
-  private void dropRemovedDisabledPlugins(Multimap<String, Path> jars) {
+  private void dropRemovedDisabledPlugins(SetMultimap<String, Path> jars) {
     Set<String> unload = Sets.newHashSet(disabled.keySet());
     for (Map.Entry<String, Collection<Path>> entry : jars.asMap().entrySet()) {
       for (Path path : entry.getValue()) {
@@ -644,7 +644,7 @@ public class PluginLoader implements LifecycleListener {
   // Only one active plugin per plugin name can exist for each plugin name.
   // Filter out disabled plugins and transform the multimap to a map
   private static Map<String, Path> filterDisabled(
-      Multimap<String, Path> pluginPaths) {
+      SetMultimap<String, Path> pluginPaths) {
     Map<String, Path> activePlugins = Maps.newHashMapWithExpectedSize(
         pluginPaths.keys().size());
     for (String name : pluginPaths.keys()) {
@@ -667,9 +667,9 @@ public class PluginLoader implements LifecycleListener {
   //
   // NOTE: Bear in mind that the plugin name can be reassigned after load by the
   //       Server plugin provider.
-  public Multimap<String, Path> prunePlugins(Path pluginsDir) {
+  public SetMultimap<String, Path> prunePlugins(Path pluginsDir) {
     List<Path> pluginPaths = scanPathsInPluginsDirectory(pluginsDir);
-    Multimap<String, Path> map;
+    SetMultimap<String, Path> map;
     map = asMultimap(pluginPaths);
     for (String plugin : map.keySet()) {
       Collection<Path> files = map.asMap().get(plugin);
@@ -735,8 +735,8 @@ public class PluginLoader implements LifecycleListener {
     return null;
   }
 
-  private Multimap<String, Path> asMultimap(List<Path> plugins) {
+  private SetMultimap<String, Path> asMultimap(List<Path> plugins) {
-    Multimap<String, Path> map = LinkedHashMultimap.create();
+    SetMultimap<String, Path> map = LinkedHashMultimap.create();
     for (Path srcPath : plugins) {
       map.put(getPluginName(srcPath), srcPath);
     }

gerrit-server/src/main/java/com/google/gerrit/server/project/PermissionCollection.java

@@ -18,9 +18,9 @@ import static com.google.common.base.MoreObjects.firstNonNull;
 import static com.google.gerrit.server.project.RefPattern.isRE;
 
 import com.google.auto.value.AutoValue;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.AccessSection;
@@ -118,7 +118,7 @@ public class PermissionCollection {
       HashMap<String, List<PermissionRule>> permissions = new HashMap<>();
       HashMap<String, List<PermissionRule>> overridden = new HashMap<>();
       Map<PermissionRule, ProjectRef> ruleProps = Maps.newIdentityHashMap();
-      Multimap<Project.NameKey, String> exclusivePermissionsByProject =
+      ListMultimap<Project.NameKey, String> exclusivePermissionsByProject =
           MultimapBuilder.hashKeys().arrayListValues().build();
       for (AccessSection section : sections) {
         Project.NameKey project = sectionToProject.get(section);

gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeData.java

@@ -24,12 +24,10 @@ import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
-import com.google.common.collect.Multimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.SubmitRecord;
 import com.google.gerrit.common.data.SubmitTypeRecord;
@@ -352,7 +350,7 @@ public class ChangeData {
   private Map<Account.Id, Ref> draftsByUser;
   @Deprecated
   private Set<Account.Id> starredByUser;
-  private ImmutableMultimap<Account.Id, String> stars;
+  private ImmutableListMultimap<Account.Id, String> stars;
   private ImmutableMap<Account.Id, StarRef> starRefs;
   private ReviewerSet reviewers;
   private List<ReviewerStatusUpdate> reviewerUpdates;
@@ -1230,13 +1228,13 @@ public class ChangeData {
     this.starredByUser = starredByUser;
   }
 
-  public ImmutableMultimap<Account.Id, String> stars() throws OrmException {
+  public ImmutableListMultimap<Account.Id, String> stars() throws OrmException {
     if (stars == null) {
       if (!lazyLoad) {
-        return ImmutableMultimap.of();
+        return ImmutableListMultimap.of();
       }
-      ImmutableMultimap.Builder<Account.Id, String> b =
+      ImmutableListMultimap.Builder<Account.Id, String> b =
-          ImmutableMultimap.builder();
+          ImmutableListMultimap.builder();
       for (Map.Entry<Account.Id, StarRef> e : starRefs().entrySet()) {
         b.putAll(e.getKey(), e.getValue().labels());
       }
@@ -1245,8 +1243,8 @@ public class ChangeData {
     return stars;
   }
 
-  public void setStars(Multimap<Account.Id, String> stars) {
+  public void setStars(ListMultimap<Account.Id, String> stars) {
-    this.stars = ImmutableMultimap.copyOf(stars);
+    this.stars = ImmutableListMultimap.copyOf(stars);
   }
 
   public ImmutableMap<Account.Id, StarRef> starRefs() throws OrmException {

gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_108.java

@@ -16,7 +16,7 @@ package com.google.gerrit.server.schema;
 
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
@@ -100,9 +100,9 @@ public class Schema_108 extends SchemaVersion {
       }
     }
 
-    Multimap<ObjectId, Ref> changeRefsBySha =
+    ListMultimap<ObjectId, Ref> changeRefsBySha =
         MultimapBuilder.hashKeys().arrayListValues().build();
-    Multimap<ObjectId, PatchSet.Id> patchSetsBySha =
+    ListMultimap<ObjectId, PatchSet.Id> patchSetsBySha =
         MultimapBuilder.hashKeys().arrayListValues().build();
     for (Ref ref : refdb.getRefs(RefNames.REFS_CHANGES).values()) {
       ObjectId id = ref.getObjectId();
@@ -132,7 +132,7 @@ public class Schema_108 extends SchemaVersion {
   }
 
   private static void updateGroups(ReviewDb db, GroupCollector collector,
-      Multimap<ObjectId, PatchSet.Id> patchSetsBySha) throws OrmException {
+      ListMultimap<ObjectId, PatchSet.Id> patchSetsBySha) throws OrmException {
     Map<PatchSet.Id, PatchSet> patchSets =
         db.patchSets().toMap(db.patchSets().get(patchSetsBySha.values()));
     for (Map.Entry<ObjectId, Collection<String>> e

gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_123.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.server.schema;
 
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
@@ -57,7 +57,7 @@ public class Schema_123 extends SchemaVersion {
   @Override
   protected void migrateData(ReviewDb db, UpdateUI ui)
       throws OrmException, SQLException {
-    Multimap<Account.Id, Change.Id> imports =
+    ListMultimap<Account.Id, Change.Id> imports =
         MultimapBuilder.hashKeys().arrayListValues().build();
     try (Statement stmt = ((JdbcSchema) db).getConnection().createStatement();
       ResultSet rs = stmt.executeQuery(

gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_124.java

@@ -17,7 +17,7 @@ package com.google.gerrit.server.schema;
 import static java.util.Comparator.comparing;
 
 import com.google.common.base.Strings;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Ordering;
 import com.google.gerrit.reviewdb.client.Account;
@@ -71,7 +71,7 @@ public class Schema_124 extends SchemaVersion {
   @Override
   protected void migrateData(ReviewDb db, UpdateUI ui)
       throws OrmException, SQLException {
-    Multimap<Account.Id, AccountSshKey> imports =
+    ListMultimap<Account.Id, AccountSshKey> imports =
         MultimapBuilder.hashKeys().arrayListValues().build();
     try (Statement stmt = ((JdbcSchema) db).getConnection().createStatement();
       ResultSet rs = stmt.executeQuery(

gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_139.java

@@ -16,7 +16,7 @@ package com.google.gerrit.server.schema;
 
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.ArrayListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Project;
@@ -73,7 +73,7 @@ public class Schema_139 extends SchemaVersion {
  @Override
  protected void migrateData(ReviewDb db, UpdateUI ui)
      throws OrmException, SQLException {
-   Multimap<Account.Id, ProjectWatch> imports = ArrayListMultimap.create();
+   ListMultimap<Account.Id, ProjectWatch> imports = ArrayListMultimap.create();
    try (Statement stmt = ((JdbcSchema) db).getConnection().createStatement();
        ResultSet rs = stmt.executeQuery(
          "SELECT "
@@ -183,4 +183,4 @@ public class Schema_139 extends SchemaVersion {
      abstract ProjectWatch build();
    }
  }
-}
+}

gerrit-server/src/test/java/com/google/gerrit/server/git/GroupCollectorTest.java

@@ -17,9 +17,8 @@ package com.google.gerrit.server.git;
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.SortedSetMultimap;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 
@@ -47,7 +46,7 @@ public class GroupCollectorTest {
     RevCommit branchTip = tr.commit().create();
     RevCommit a = tr.commit().parent(branchTip).create();
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(a, branchTip),
         patchSets(),
         groups());
@@ -62,7 +61,7 @@ public class GroupCollectorTest {
     RevCommit a = tr.commit().parent(branchTip).create();
     RevCommit b = tr.commit().parent(a).create();
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(b, branchTip),
         patchSets(),
         groups());
@@ -79,7 +78,7 @@ public class GroupCollectorTest {
     RevCommit b = tr.commit().parent(a).create();
 
     String group = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(b, branchTip),
         patchSets().put(a, psId(1, 1)),
         groups().put(psId(1, 1), group));
@@ -95,7 +94,7 @@ public class GroupCollectorTest {
     RevCommit a = tr.commit().parent(branchTip).create();
     RevCommit b = tr.commit().parent(a).create();
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(b, branchTip),
         patchSets().put(a, psId(1, 1)),
         groups());
@@ -111,7 +110,7 @@ public class GroupCollectorTest {
     RevCommit b = tr.commit().parent(branchTip).create();
     RevCommit m = tr.commit().parent(a).parent(b).create();
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets(),
         groups());
@@ -129,7 +128,7 @@ public class GroupCollectorTest {
     RevCommit m = tr.commit().parent(a).parent(b).create();
 
     String group = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets().put(b, psId(1, 1)),
         groups().put(psId(1, 1), group));
@@ -150,7 +149,7 @@ public class GroupCollectorTest {
 
     String group1 = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";
     String group2 = "1234567812345678123456781234567812345678";
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets()
             .put(a, psId(1, 1))
@@ -176,7 +175,7 @@ public class GroupCollectorTest {
     String group1 = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";
     String group2a = "1234567812345678123456781234567812345678";
     String group2b = "ef123456ef123456ef123456ef123456ef123456";
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets()
             .put(a, psId(1, 1))
@@ -202,7 +201,7 @@ public class GroupCollectorTest {
     RevCommit m = tr.commit().parent(branchTip).parent(a).create();
 
     String group = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets().put(a, psId(1, 1)),
         groups().put(psId(1, 1), group));
@@ -218,7 +217,7 @@ public class GroupCollectorTest {
     RevCommit a = tr.commit().parent(branchTip).create();
     RevCommit m = tr.commit().parent(branchTip).parent(a).create();
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets(),
         groups());
@@ -237,7 +236,7 @@ public class GroupCollectorTest {
     RevCommit m1 = tr.commit().parent(b).parent(c).create();
     RevCommit m2 = tr.commit().parent(a).parent(m1).create();
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m2, branchTip),
         patchSets(),
         groups());
@@ -259,7 +258,7 @@ public class GroupCollectorTest {
     assertThat(m.getParentCount()).isEqualTo(2);
     assertThat(m.getParent(0)).isEqualTo(m.getParent(1));
 
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets(),
         groups());
@@ -279,7 +278,7 @@ public class GroupCollectorTest {
 
     String group1 = "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef";
     String group2 = "1234567812345678123456781234567812345678";
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         newWalk(m, branchTip),
         patchSets()
             .put(a, psId(1, 1))
@@ -307,7 +306,7 @@ public class GroupCollectorTest {
     rw.markStart(rw.parseCommit(d));
     // Schema upgrade case: all commits are existing patch sets, but none have
     // groups assigned yet.
-    Multimap<ObjectId, String> groups = collectGroups(
+    SortedSetMultimap<ObjectId, String> groups = collectGroups(
         rw,
         patchSets()
             .put(branchTip, psId(1, 1))
@@ -339,9 +338,9 @@ public class GroupCollectorTest {
     return rw;
   }
 
-  private static Multimap<ObjectId, String> collectGroups(
+  private static SortedSetMultimap<ObjectId, String> collectGroups(
       RevWalk rw,
-      ImmutableMultimap.Builder<ObjectId, PatchSet.Id> patchSetsBySha,
+      ImmutableListMultimap.Builder<ObjectId, PatchSet.Id> patchSetsBySha,
       ImmutableListMultimap.Builder<PatchSet.Id, String> groupLookup)
       throws Exception {
     GroupCollector gc =
@@ -355,8 +354,9 @@ public class GroupCollectorTest {
 
   // Helper methods for constructing various map arguments, to avoid lots of
   // type specifications.
-  private static ImmutableMultimap.Builder<ObjectId, PatchSet.Id> patchSets() {
+  private static ImmutableListMultimap.Builder<ObjectId, PatchSet.Id>
-    return ImmutableMultimap.builder();
+      patchSets() {
+    return ImmutableListMultimap.builder();
   }
 
   private static ImmutableListMultimap.Builder<PatchSet.Id, String> groups() {

gerrit-server/src/test/java/com/google/gerrit/server/index/change/StalenessCheckerTest.java

@@ -21,7 +21,7 @@ import static com.google.gerrit.testutil.TestChanges.newChange;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.stream.Collectors.toList;
 
-import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.ListMultimap;
 import com.google.gerrit.reviewdb.client.Account;
@@ -194,7 +194,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name()),
                     P2, RefState.create(ref2, id2.name())),
-                ImmutableMultimap.of()))
+                ImmutableListMultimap.of()))
         .isFalse();
 
     // Wrong ref value.
@@ -204,7 +204,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, SHA1),
                     P2, RefState.create(ref2, id2.name())),
-                ImmutableMultimap.of()))
+                ImmutableListMultimap.of()))
         .isTrue();
 
     // Swapped repos.
@@ -214,7 +214,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id2.name()),
                     P2, RefState.create(ref2, id1.name())),
-                ImmutableMultimap.of()))
+                ImmutableListMultimap.of()))
         .isTrue();
 
     // Two refs in same repo, not stale.
@@ -227,7 +227,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name()),
                     P1, RefState.create(ref3, id3.name())),
-                ImmutableMultimap.of()))
+                ImmutableListMultimap.of()))
         .isFalse();
 
     // Ignore ref not mentioned.
@@ -236,7 +236,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 repoManager, C,
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name())),
-                ImmutableMultimap.of()))
+                ImmutableListMultimap.of()))
         .isFalse();
 
     // One ref wrong.
@@ -246,7 +246,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name()),
                     P1, RefState.create(ref3, SHA1)),
-                ImmutableMultimap.of()))
+                ImmutableListMultimap.of()))
         .isTrue();
   }
 
@@ -261,7 +261,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 repoManager, C,
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name())),
-                ImmutableMultimap.of(
+                ImmutableListMultimap.of(
                     P1, RefStatePattern.create("refs/heads/*"))))
         .isFalse();
 
@@ -273,7 +273,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 repoManager, C,
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name())),
-                ImmutableMultimap.of(
+                ImmutableListMultimap.of(
                     P1, RefStatePattern.create("refs/heads/*"))))
         .isTrue();
     assertThat(
@@ -282,7 +282,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name()),
                     P1, RefState.create(ref2, id2.name())),
-                ImmutableMultimap.of(
+                ImmutableListMultimap.of(
                     P1, RefStatePattern.create("refs/heads/*"))))
         .isFalse();
   }
@@ -299,7 +299,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 repoManager, C,
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name())),
-                ImmutableMultimap.of(
+                ImmutableListMultimap.of(
                     P1, RefStatePattern.create("refs/*/foo"))))
         .isFalse();
 
@@ -311,7 +311,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 repoManager, C,
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name())),
-                ImmutableMultimap.of(
+                ImmutableListMultimap.of(
                     P1, RefStatePattern.create("refs/*/foo"))))
         .isTrue();
     assertThat(
@@ -320,7 +320,7 @@ public class StalenessCheckerTest extends GerritBaseTests {
                 ImmutableSetMultimap.of(
                     P1, RefState.create(ref1, id1.name()),
                     P1, RefState.create(ref3, id3.name())),
-                ImmutableMultimap.of(
+                ImmutableListMultimap.of(
                     P1, RefStatePattern.create("refs/*/foo"))))
         .isFalse();
   }

gerrit-server/src/test/java/com/google/gerrit/server/notedb/ChangeNotesTest.java

@@ -26,7 +26,6 @@ import static org.junit.Assert.fail;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableTable;
 import com.google.common.collect.Iterables;
@@ -350,7 +349,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     notes = newNotes(c);
     assertThat(notes.getApprovals()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
             psa.getPatchSetId(),
             new PatchSetApproval(psa.getKey(), (short) 0, update.getWhen())));
   }
@@ -375,7 +374,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     notes = newNotes(c);
     assertThat(notes.getApprovals()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
             psa.getPatchSetId(),
             new PatchSetApproval(psa.getKey(), (short) 0, update.getWhen())));
 
@@ -1452,7 +1451,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getComments())
-        .isEqualTo(ImmutableMultimap.of(revId, comment));
+        .isEqualTo(ImmutableListMultimap.of(revId, comment));
   }
 
   @Test
@@ -1472,7 +1471,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getComments())
-        .isEqualTo(ImmutableMultimap.of(revId, comment));
+        .isEqualTo(ImmutableListMultimap.of(revId, comment));
   }
 
   @Test
@@ -1492,7 +1491,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getComments())
-        .isEqualTo(ImmutableMultimap.of(revId, comment));
+        .isEqualTo(ImmutableListMultimap.of(revId, comment));
   }
 
   @Test
@@ -1512,7 +1511,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getComments())
-        .isEqualTo(ImmutableMultimap.of(revId, comment));
+        .isEqualTo(ImmutableListMultimap.of(revId, comment));
   }
 
   @Test
@@ -1822,7 +1821,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
       }
     }
     assertThat(notes.getComments()).isEqualTo(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
             revId, comment1,
             revId, comment2,
             revId, comment3));
@@ -1879,7 +1878,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
       }
     }
     assertThat(notes.getComments())
-        .isEqualTo(ImmutableMultimap.of(revId, comment));
+        .isEqualTo(ImmutableListMultimap.of(revId, comment));
   }
 
   @Test
@@ -1934,7 +1933,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
       }
     }
     assertThat(notes.getComments())
-        .isEqualTo(ImmutableMultimap.of(new RevId(comment.revId), comment));
+        .isEqualTo(ImmutableListMultimap.of(new RevId(comment.revId), comment));
   }
 
   @Test
@@ -1969,7 +1968,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     update.commit();
 
     assertThat(newNotes(c).getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
             new RevId(rev1), commentForBase,
             new RevId(rev2), commentForPS));
   }
@@ -2004,7 +2003,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     update.commit();
 
     assertThat(newNotes(c).getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
           new RevId(rev), comment1,
           new RevId(rev), comment2)).inOrder();
   }
@@ -2039,7 +2038,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     update.commit();
 
     assertThat(newNotes(c).getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
           new RevId(rev), comment1,
           new RevId(rev), comment2)).inOrder();
   }
@@ -2077,7 +2076,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     update.commit();
 
     assertThat(newNotes(c).getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
           new RevId(rev1), comment1,
           new RevId(rev2), comment2));
   }
@@ -2103,7 +2102,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getDraftComments(otherUserId)).containsExactlyEntriesIn(
-        ImmutableMultimap.of(new RevId(rev), comment1));
+        ImmutableListMultimap.of(new RevId(rev), comment1));
     assertThat(notes.getComments()).isEmpty();
 
     update = newUpdate(c, otherUser);
@@ -2114,7 +2113,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     notes = newNotes(c);
     assertThat(notes.getDraftComments(otherUserId)).isEmpty();
     assertThat(notes.getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(new RevId(rev), comment1));
+        ImmutableListMultimap.of(new RevId(rev), comment1));
   }
 
   @Test
@@ -2146,7 +2145,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getDraftComments(otherUserId)).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
           new RevId(rev), comment1,
           new RevId(rev), comment2)).inOrder();
     assertThat(notes.getComments()).isEmpty();
@@ -2159,9 +2158,9 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     notes = newNotes(c);
     assertThat(notes.getDraftComments(otherUserId)).containsExactlyEntriesIn(
-        ImmutableMultimap.of(new RevId(rev), comment2));
+        ImmutableListMultimap.of(new RevId(rev), comment2));
     assertThat(notes.getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(new RevId(rev), comment1));
+        ImmutableListMultimap.of(new RevId(rev), comment1));
   }
 
   @Test
@@ -2194,7 +2193,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
 
     ChangeNotes notes = newNotes(c);
     assertThat(notes.getDraftComments(otherUserId)).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
             new RevId(rev1), baseComment,
             new RevId(rev2), psComment));
     assertThat(notes.getComments()).isEmpty();
@@ -2210,7 +2209,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     notes = newNotes(c);
     assertThat(notes.getDraftComments(otherUserId)).isEmpty();
     assertThat(notes.getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(
+        ImmutableListMultimap.of(
             new RevId(rev1), baseComment,
             new RevId(rev2), psComment));
   }
@@ -2373,7 +2372,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     update.commit();
 
     assertThat(newNotes(c).getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(new RevId(rev), comment));
+        ImmutableListMultimap.of(new RevId(rev), comment));
   }
 
   @Test
@@ -2393,7 +2392,7 @@ public class ChangeNotesTest extends AbstractChangeNotesTest {
     update.commit();
 
     assertThat(newNotes(c).getComments()).containsExactlyEntriesIn(
-        ImmutableMultimap.of(new RevId(rev), comment));
+        ImmutableListMultimap.of(new RevId(rev), comment));
   }
 
   @Test

gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshAutoRegisterModuleGenerator.java

@@ -18,7 +18,7 @@ import static com.google.gerrit.server.plugins.AutoRegisterUtil.calculateBindAnn
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.LinkedListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.extensions.annotations.Export;
 import com.google.gerrit.server.plugins.InvalidPluginException;
 import com.google.gerrit.server.plugins.ModuleGenerator;
@@ -36,7 +36,8 @@ class SshAutoRegisterModuleGenerator
     extends AbstractModule
     implements ModuleGenerator {
   private final Map<String, Class<Command>> commands = new HashMap<>();
-  private final Multimap<TypeLiteral<?>, Class<?>> listeners = LinkedListMultimap.create();
+  private final ListMultimap<TypeLiteral<?>, Class<?>> listeners =
+      LinkedListMultimap.create();
   private CommandName command;
 
   @Override

gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshLog.java

@@ -15,7 +15,7 @@
 package com.google.gerrit.sshd;
 
 import com.google.common.collect.ArrayListMultimap;
-import com.google.common.collect.Multimap;
+import com.google.common.collect.ListMultimap;
 import com.google.gerrit.audit.AuditService;
 import com.google.gerrit.audit.SshAuditEvent;
 import com.google.gerrit.common.TimeUtil;
@@ -156,14 +156,14 @@ class SshLog implements LifecycleListener {
     audit(context.get(), status, dcmd);
   }
 
-  private Multimap<String, ?> extractParameters(DispatchCommand dcmd) {
+  private ListMultimap<String, ?> extractParameters(DispatchCommand dcmd) {
     if (dcmd == null) {
       return ArrayListMultimap.create(0, 0);
     }
     String[] cmdArgs = dcmd.getArguments();
     String paramName = null;
     int argPos = 0;
-    Multimap<String, String> parms = ArrayListMultimap.create();
+    ListMultimap<String, String> parms = ArrayListMultimap.create();
     for (int i = 2; i < cmdArgs.length; i++) {
       String arg = cmdArgs[i];
       // -- stop parameters parsing
@@ -258,7 +258,8 @@ class SshLog implements LifecycleListener {
     audit(ctx, result, extractWhat(cmd), extractParameters(cmd));
   }
 
-  private void audit(Context ctx, Object result, String cmd, Multimap<String, ?> params) {
+  private void audit(Context ctx, Object result, String cmd,
+      ListMultimap<String, ?> params) {
     String sessionId;
     CurrentUser currentUser;
     long created;

gerrit-util-cli/src/main/java/com/google/gerrit/util/cli/CmdLineParser.java

@@ -35,9 +35,9 @@
 package com.google.gerrit.util.cli;
 
 import com.google.common.base.Strings;
-import com.google.common.collect.LinkedHashMultimap;
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
 
@@ -224,7 +224,7 @@ public class CmdLineParser {
 
   public void parseOptionMap(Map<String, String[]> parameters)
       throws CmdLineException {
-    Multimap<String, String> map = LinkedHashMultimap.create();
+    ListMultimap<String, String> map = ArrayListMultimap.create();
     for (Map.Entry<String, String[]> ent : parameters.entrySet()) {
       for (String val : ent.getValue()) {
         map.put(ent.getKey(), val);
@@ -233,7 +233,7 @@ public class CmdLineParser {
     parseOptionMap(map);
   }
 
-  public void parseOptionMap(Multimap<String, String> params)
+  public void parseOptionMap(ListMultimap<String, String> params)
       throws CmdLineException {
     List<String> tmp = Lists.newArrayListWithCapacity(2 * params.size());
     for (final String key : params.keySet()) {

plugins/cookbook-plugin

@@ -1 +1 @@
-Subproject commit 860742125749aec5444bfa44bb727153c2649893
+Subproject commit ea6c8c3949cecfd6547ce1e97d2dddbb2669e827

plugins/replication

@@ -1 +1 @@
-Subproject commit 0ed3b13df0b4f88c67ece722e56e554f8f38e83a
+Subproject commit 66f08f2460ba89b6827f4e456be1c1a948a718aa