diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/OperatorPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/OperatorPredicate.java
index 96a30ee650..9413c5dc9f 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/OperatorPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/OperatorPredicate.java
@@ -18,10 +18,10 @@ import java.util.Collection;
 
 /** Predicate to filter a field by matching value. */
 public abstract class OperatorPredicate<T> extends Predicate<T> {
-  private final String name;
-  private final String value;
+  protected final String name;
+  protected final String value;
 
-  protected OperatorPredicate(final String name, final String value) {
+  public OperatorPredicate(final String name, final String value) {
     this.name = name;
     this.value = value;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/account/AccountIsVisibleToPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/account/AccountIsVisibleToPredicate.java
index 0a74647d0f..e5ed44dcaa 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/account/AccountIsVisibleToPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/account/AccountIsVisibleToPredicate.java
@@ -20,9 +20,9 @@ import com.google.gerrit.server.query.IsVisibleToPredicate;
 import com.google.gwtorm.server.OrmException;
 
 public class AccountIsVisibleToPredicate extends IsVisibleToPredicate<AccountState> {
-  private final AccountControl accountControl;
+  protected final AccountControl accountControl;
 
-  AccountIsVisibleToPredicate(AccountControl accountControl) {
+  public AccountIsVisibleToPredicate(AccountControl accountControl) {
     super(AccountQueryBuilder.FIELD_VISIBLETO, describe(accountControl.getUser()));
     this.accountControl = accountControl;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AddedPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AddedPredicate.java
index b3cdd6ac97..05bf24bd26 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AddedPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AddedPredicate.java
@@ -19,7 +19,7 @@ import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
 public class AddedPredicate extends IntegerRangeChangePredicate {
-  AddedPredicate(String value) throws QueryParseException {
+  public AddedPredicate(String value) throws QueryParseException {
     super(ChangeField.ADDED, value);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AfterPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AfterPredicate.java
index 7d51217203..b9c46947ee 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AfterPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AfterPredicate.java
@@ -20,9 +20,9 @@ import com.google.gwtorm.server.OrmException;
 import java.util.Date;
 
 public class AfterPredicate extends TimestampRangeChangePredicate {
-  private final Date cut;
+  protected final Date cut;
 
-  AfterPredicate(String value) throws QueryParseException {
+  public AfterPredicate(String value) throws QueryParseException {
     super(ChangeField.UPDATED, ChangeQueryBuilder.FIELD_BEFORE, value);
     cut = parse(value);
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AgePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AgePredicate.java
index 0cd76bb2c7..a5f49653ce 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AgePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AgePredicate.java
@@ -25,9 +25,9 @@ import com.google.gwtorm.server.OrmException;
 import java.sql.Timestamp;
 
 public class AgePredicate extends TimestampRangeChangePredicate {
-  private final long cut;
+  protected final long cut;
 
-  AgePredicate(String value) {
+  public AgePredicate(String value) {
     super(ChangeField.UPDATED, ChangeQueryBuilder.FIELD_AGE, value);
 
     long s = ConfigUtil.getTimeUnit(getValue(), 0, SECONDS);
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AssigneePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AssigneePredicate.java
index 38622eddb0..848fd09101 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AssigneePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AssigneePredicate.java
@@ -18,10 +18,10 @@ import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class AssigneePredicate extends ChangeIndexPredicate {
-  private final Account.Id id;
+public class AssigneePredicate extends ChangeIndexPredicate {
+  protected final Account.Id id;
 
-  AssigneePredicate(Account.Id id) {
+  public AssigneePredicate(Account.Id id) {
     super(ChangeField.ASSIGNEE, id.toString());
     this.id = id;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AuthorPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AuthorPredicate.java
index dccd17e51d..3ee3352345 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AuthorPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/AuthorPredicate.java
@@ -22,7 +22,7 @@ import com.google.gwtorm.server.OrmException;
 import java.io.IOException;
 
 public class AuthorPredicate extends ChangeIndexPredicate {
-  AuthorPredicate(String value) {
+  public AuthorPredicate(String value) {
     super(AUTHOR, FIELD_AUTHOR, value.toLowerCase());
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BeforePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BeforePredicate.java
index 9e443c9eb3..bc57f15934 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BeforePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BeforePredicate.java
@@ -20,9 +20,9 @@ import com.google.gwtorm.server.OrmException;
 import java.util.Date;
 
 public class BeforePredicate extends TimestampRangeChangePredicate {
-  private final Date cut;
+  protected final Date cut;
 
-  BeforePredicate(String value) throws QueryParseException {
+  public BeforePredicate(String value) throws QueryParseException {
     super(ChangeField.UPDATED, ChangeQueryBuilder.FIELD_BEFORE, value);
     cut = parse(value);
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BooleanPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BooleanPredicate.java
index ad43c5f000..31e3ee16f1 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BooleanPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/BooleanPredicate.java
@@ -18,10 +18,10 @@ import com.google.gerrit.server.index.FieldDef;
 import com.google.gerrit.server.index.FieldDef.FillArgs;
 import com.google.gwtorm.server.OrmException;
 
-class BooleanPredicate extends ChangeIndexPredicate {
-  private final FillArgs args;
+public class BooleanPredicate extends ChangeIndexPredicate {
+  protected final FillArgs args;
 
-  BooleanPredicate(FieldDef<ChangeData, String> field, FillArgs args) {
+  public BooleanPredicate(FieldDef<ChangeData, String> field, FillArgs args) {
     super(field, "1");
     this.args = args;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIdPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIdPredicate.java
index 85d433a5b1..d541d189cf 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIdPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIdPredicate.java
@@ -19,8 +19,8 @@ import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
 /** Predicate over Change-Id strings (aka Change.Key). */
-class ChangeIdPredicate extends ChangeIndexPredicate {
-  ChangeIdPredicate(String id) {
+public class ChangeIdPredicate extends ChangeIndexPredicate {
+  public ChangeIdPredicate(String id) {
     super(ChangeField.ID, ChangeQueryBuilder.FIELD_CHANGE, id);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIsVisibleToPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIsVisibleToPredicate.java
index 8db62a7e1b..632ec040a0 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIsVisibleToPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeIsVisibleToPredicate.java
@@ -24,13 +24,13 @@ import com.google.gerrit.server.query.IsVisibleToPredicate;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Provider;
 
-class ChangeIsVisibleToPredicate extends IsVisibleToPredicate<ChangeData> {
-  private final Provider<ReviewDb> db;
-  private final ChangeNotes.Factory notesFactory;
-  private final ChangeControl.GenericFactory changeControl;
-  private final CurrentUser user;
+public class ChangeIsVisibleToPredicate extends IsVisibleToPredicate<ChangeData> {
+  protected final Provider<ReviewDb> db;
+  protected final ChangeNotes.Factory notesFactory;
+  protected final ChangeControl.GenericFactory changeControl;
+  protected final CurrentUser user;
 
-  ChangeIsVisibleToPredicate(
+  public ChangeIsVisibleToPredicate(
       Provider<ReviewDb> db,
       ChangeNotes.Factory notesFactory,
       ChangeControl.GenericFactory changeControlFactory,
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeStatusPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeStatusPredicate.java
index 9c16777773..562608eba7 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeStatusPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeStatusPredicate.java
@@ -36,9 +36,9 @@ import java.util.TreeMap;
  * <p>Status names are looked up by prefix case-insensitively.
  */
 public final class ChangeStatusPredicate extends ChangeIndexPredicate {
-  private static final TreeMap<String, Predicate<ChangeData>> PREDICATES;
-  private static final Predicate<ChangeData> CLOSED;
-  private static final Predicate<ChangeData> OPEN;
+  protected static final TreeMap<String, Predicate<ChangeData>> PREDICATES;
+  protected static final Predicate<ChangeData> CLOSED;
+  protected static final Predicate<ChangeData> OPEN;
 
   static {
     PREDICATES = new TreeMap<>();
@@ -84,9 +84,9 @@ public final class ChangeStatusPredicate extends ChangeIndexPredicate {
     return CLOSED;
   }
 
-  private final Change.Status status;
+  protected final Change.Status status;
 
-  ChangeStatusPredicate(Change.Status status) {
+  public ChangeStatusPredicate(Change.Status status) {
     super(ChangeField.STATUS, canonicalize(status));
     this.status = status;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentByPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentByPredicate.java
index 668c6f21f4..7ad7afe28a 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentByPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentByPredicate.java
@@ -21,10 +21,10 @@ import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 import java.util.Objects;
 
-class CommentByPredicate extends ChangeIndexPredicate {
-  private final Account.Id id;
+public class CommentByPredicate extends ChangeIndexPredicate {
+  protected final Account.Id id;
 
-  CommentByPredicate(Account.Id id) {
+  public CommentByPredicate(Account.Id id) {
     super(ChangeField.COMMENTBY, id.toString());
     this.id = id;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentPredicate.java
index 4779a163d4..85efe90ee6 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommentPredicate.java
@@ -21,10 +21,10 @@ import com.google.gerrit.server.query.Predicate;
 import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
-class CommentPredicate extends ChangeIndexPredicate {
-  private final ChangeIndex index;
+public class CommentPredicate extends ChangeIndexPredicate {
+  protected final ChangeIndex index;
 
-  CommentPredicate(ChangeIndex index, String value) {
+  public CommentPredicate(ChangeIndex index, String value) {
     super(ChangeField.COMMENT, value);
     this.index = index;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitPredicate.java
index 1188d5dea5..3fac217f12 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitPredicate.java
@@ -22,7 +22,7 @@ import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.server.index.FieldDef;
 import com.google.gwtorm.server.OrmException;
 
-class CommitPredicate extends ChangeIndexPredicate {
+public class CommitPredicate extends ChangeIndexPredicate {
   static FieldDef<ChangeData, ?> commitField(String id) {
     if (id.length() == OBJECT_ID_STRING_LENGTH) {
       return EXACT_COMMIT;
@@ -30,7 +30,7 @@ class CommitPredicate extends ChangeIndexPredicate {
     return COMMIT;
   }
 
-  CommitPredicate(String id) {
+  public CommitPredicate(String id) {
     super(commitField(id), id);
   }
 
@@ -45,7 +45,7 @@ class CommitPredicate extends ChangeIndexPredicate {
     return false;
   }
 
-  private boolean equals(PatchSet p, String id) {
+  protected boolean equals(PatchSet p, String id) {
     boolean exact = getField() == EXACT_COMMIT;
     String rev = p.getRevision() != null ? p.getRevision().get() : null;
     return (exact && id.equals(rev)) || (!exact && rev != null && rev.startsWith(id));
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitterPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitterPredicate.java
index cd1f3b2f61..797cb9d04f 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitterPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/CommitterPredicate.java
@@ -22,7 +22,7 @@ import com.google.gwtorm.server.OrmException;
 import java.io.IOException;
 
 public class CommitterPredicate extends ChangeIndexPredicate {
-  CommitterPredicate(String value) {
+  public CommitterPredicate(String value) {
     super(COMMITTER, FIELD_COMMITTER, value.toLowerCase());
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ConflictsPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ConflictsPredicate.java
index 9b4589001f..4d8c6a1a88 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ConflictsPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ConflictsPredicate.java
@@ -45,19 +45,19 @@ import org.eclipse.jgit.revwalk.filter.RevFilter;
 import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.treewalk.filter.TreeFilter;
 
-class ConflictsPredicate extends OrPredicate<ChangeData> {
+public class ConflictsPredicate extends OrPredicate<ChangeData> {
   // UI code may depend on this string, so use caution when changing.
-  private static final String TOO_MANY_FILES = "too many files to find conflicts";
+  protected static final String TOO_MANY_FILES = "too many files to find conflicts";
 
-  private final String value;
+  protected final String value;
 
-  ConflictsPredicate(Arguments args, String value, List<Change> changes)
+  public ConflictsPredicate(Arguments args, String value, List<Change> changes)
       throws QueryParseException, OrmException {
     super(predicates(args, value, changes));
     this.value = value;
   }
 
-  private static List<Predicate<ChangeData>> predicates(
+  public static List<Predicate<ChangeData>> predicates(
       final Arguments args, String value, List<Change> changes)
       throws QueryParseException, OrmException {
     int indexTerms = 0;
@@ -160,7 +160,7 @@ class ConflictsPredicate extends OrPredicate<ChangeData> {
     return changePredicates;
   }
 
-  private static List<String> listFiles(Change c, Arguments args, ChangeDataCache changeDataCache)
+  public static List<String> listFiles(Change c, Arguments args, ChangeDataCache changeDataCache)
       throws OrmException {
     try (Repository repo = args.repoManager.openRepository(c.getProject());
         RevWalk rw = new RevWalk(repo)) {
@@ -200,17 +200,17 @@ class ConflictsPredicate extends OrPredicate<ChangeData> {
     return ChangeQueryBuilder.FIELD_CONFLICTS + ":" + value;
   }
 
-  private static class ChangeDataCache {
-    private final Change change;
-    private final Provider<ReviewDb> db;
-    private final ChangeData.Factory changeDataFactory;
-    private final ProjectCache projectCache;
+  public static class ChangeDataCache {
+    protected final Change change;
+    protected final Provider<ReviewDb> db;
+    protected final ChangeData.Factory changeDataFactory;
+    protected final ProjectCache projectCache;
 
-    private ObjectId testAgainst;
-    private ProjectState projectState;
-    private Iterable<ObjectId> alreadyAccepted;
+    protected ObjectId testAgainst;
+    protected ProjectState projectState;
+    protected Iterable<ObjectId> alreadyAccepted;
 
-    ChangeDataCache(
+    public ChangeDataCache(
         Change change,
         Provider<ReviewDb> db,
         ChangeData.Factory changeDataFactory,
@@ -221,7 +221,7 @@ class ConflictsPredicate extends OrPredicate<ChangeData> {
       this.projectCache = projectCache;
     }
 
-    ObjectId getTestAgainst() throws OrmException {
+    protected ObjectId getTestAgainst() throws OrmException {
       if (testAgainst == null) {
         testAgainst =
             ObjectId.fromString(
@@ -230,7 +230,7 @@ class ConflictsPredicate extends OrPredicate<ChangeData> {
       return testAgainst;
     }
 
-    ProjectState getProjectState() {
+    protected ProjectState getProjectState() {
       if (projectState == null) {
         projectState = projectCache.get(change.getProject());
         if (projectState == null) {
@@ -240,7 +240,7 @@ class ConflictsPredicate extends OrPredicate<ChangeData> {
       return projectState;
     }
 
-    Iterable<ObjectId> getAlreadyAccepted(Repository repo) throws IOException {
+    protected Iterable<ObjectId> getAlreadyAccepted(Repository repo) throws IOException {
       if (alreadyAccepted == null) {
         alreadyAccepted = SubmitDryRun.getAlreadyAccepted(repo);
       }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeletedPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeletedPredicate.java
index 9e49269cf1..9c46da8026 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeletedPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeletedPredicate.java
@@ -19,7 +19,7 @@ import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
 public class DeletedPredicate extends IntegerRangeChangePredicate {
-  DeletedPredicate(String value) throws QueryParseException {
+  public DeletedPredicate(String value) throws QueryParseException {
     super(ChangeField.DELETED, value);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeltaPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeltaPredicate.java
index ce33225b59..68a4b84c99 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeltaPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DeltaPredicate.java
@@ -19,7 +19,7 @@ import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
 public class DeltaPredicate extends IntegerRangeChangePredicate {
-  DeltaPredicate(String value) throws QueryParseException {
+  public DeltaPredicate(String value) throws QueryParseException {
     super(ChangeField.DELTA, value);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DestinationPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DestinationPredicate.java
index 809e7a1b4c..4e8d30dd90 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DestinationPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/DestinationPredicate.java
@@ -19,10 +19,10 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gwtorm.server.OrmException;
 import java.util.Set;
 
-class DestinationPredicate extends ChangeOperatorPredicate {
-  Set<Branch.NameKey> destinations;
+public class DestinationPredicate extends ChangeOperatorPredicate {
+  protected Set<Branch.NameKey> destinations;
 
-  DestinationPredicate(Set<Branch.NameKey> destinations, String value) {
+  public DestinationPredicate(Set<Branch.NameKey> destinations, String value) {
     super(ChangeQueryBuilder.FIELD_DESTINATION, value);
     this.destinations = destinations;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EditByPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EditByPredicate.java
index 8be5235590..3238dc9faa 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EditByPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EditByPredicate.java
@@ -18,10 +18,10 @@ import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class EditByPredicate extends ChangeIndexPredicate {
-  private final Account.Id id;
+public class EditByPredicate extends ChangeIndexPredicate {
+  protected final Account.Id id;
 
-  EditByPredicate(Account.Id id) {
+  public EditByPredicate(Account.Id id) {
     super(ChangeField.EDITBY, id.toString());
     this.id = id;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsFilePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsFilePredicate.java
index fb6c56b2f9..0221b28779 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsFilePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsFilePredicate.java
@@ -19,8 +19,8 @@ import com.google.gerrit.server.query.Predicate;
 import com.google.gerrit.server.query.change.ChangeQueryBuilder.Arguments;
 import com.google.gwtorm.server.OrmException;
 
-class EqualsFilePredicate extends ChangeIndexPredicate {
-  static Predicate<ChangeData> create(Arguments args, String value) {
+public class EqualsFilePredicate extends ChangeIndexPredicate {
+  public static Predicate<ChangeData> create(Arguments args, String value) {
     Predicate<ChangeData> eqPath = new EqualsPathPredicate(ChangeQueryBuilder.FIELD_FILE, value);
     if (!args.getSchema().hasField(ChangeField.FILE_PART)) {
       return eqPath;
@@ -28,7 +28,7 @@ class EqualsFilePredicate extends ChangeIndexPredicate {
     return Predicate.or(eqPath, new EqualsFilePredicate(value));
   }
 
-  private final String value;
+  protected final String value;
 
   private EqualsFilePredicate(String value) {
     super(ChangeField.FILE_PART, ChangeQueryBuilder.FIELD_FILE, value);
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsLabelPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsLabelPredicate.java
index a5814fe3d6..1917d6f7e4 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsLabelPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsLabelPredicate.java
@@ -31,17 +31,18 @@ import com.google.gerrit.server.project.ProjectState;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Provider;
 
-class EqualsLabelPredicate extends ChangeIndexPredicate {
-  private final ProjectCache projectCache;
-  private final PermissionBackend permissionBackend;
-  private final IdentifiedUser.GenericFactory userFactory;
-  private final Provider<ReviewDb> dbProvider;
-  private final String label;
-  private final int expVal;
-  private final Account.Id account;
-  private final AccountGroup.UUID group;
+public class EqualsLabelPredicate extends ChangeIndexPredicate {
+  protected final ProjectCache projectCache;
+  protected final PermissionBackend permissionBackend;
+  protected final IdentifiedUser.GenericFactory userFactory;
+  protected final Provider<ReviewDb> dbProvider;
+  protected final String label;
+  protected final int expVal;
+  protected final Account.Id account;
+  protected final AccountGroup.UUID group;
 
-  EqualsLabelPredicate(LabelPredicate.Args args, String label, int expVal, Account.Id account) {
+  public EqualsLabelPredicate(
+      LabelPredicate.Args args, String label, int expVal, Account.Id account) {
     super(ChangeField.LABEL, ChangeField.formatLabel(label, expVal, account));
     this.permissionBackend = args.permissionBackend;
     this.projectCache = args.projectCache;
@@ -91,7 +92,7 @@ class EqualsLabelPredicate extends ChangeIndexPredicate {
     return false;
   }
 
-  private static LabelType type(LabelTypes types, String toFind) {
+  protected static LabelType type(LabelTypes types, String toFind) {
     if (types.byLabel(toFind) != null) {
       return types.byLabel(toFind);
     }
@@ -104,7 +105,7 @@ class EqualsLabelPredicate extends ChangeIndexPredicate {
     return null;
   }
 
-  private boolean match(ChangeData cd, short value, Account.Id approver, LabelType type) {
+  protected boolean match(ChangeData cd, short value, Account.Id approver, LabelType type) {
     if (value != expVal) {
       return false;
     }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsPathPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsPathPredicate.java
index 9d841f394e..dabebb067c 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsPathPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/EqualsPathPredicate.java
@@ -19,10 +19,10 @@ import com.google.gwtorm.server.OrmException;
 import java.util.Collections;
 import java.util.List;
 
-class EqualsPathPredicate extends ChangeIndexPredicate {
-  private final String value;
+public class EqualsPathPredicate extends ChangeIndexPredicate {
+  protected final String value;
 
-  EqualsPathPredicate(String fieldName, String value) {
+  public EqualsPathPredicate(String fieldName, String value) {
     super(ChangeField.PATH, fieldName, value);
     this.value = value;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ExactTopicPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ExactTopicPredicate.java
index 510910e9be..dc85eceb34 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ExactTopicPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ExactTopicPredicate.java
@@ -19,8 +19,8 @@ import static com.google.gerrit.server.index.change.ChangeField.EXACT_TOPIC;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gwtorm.server.OrmException;
 
-class ExactTopicPredicate extends ChangeIndexPredicate {
-  ExactTopicPredicate(String topic) {
+public class ExactTopicPredicate extends ChangeIndexPredicate {
+  public ExactTopicPredicate(String topic) {
     super(EXACT_TOPIC, topic);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/FuzzyTopicPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/FuzzyTopicPredicate.java
index 5651544d22..5f3b621081 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/FuzzyTopicPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/FuzzyTopicPredicate.java
@@ -24,10 +24,10 @@ import com.google.gerrit.server.query.Predicate;
 import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
-class FuzzyTopicPredicate extends ChangeIndexPredicate {
-  private final ChangeIndex index;
+public class FuzzyTopicPredicate extends ChangeIndexPredicate {
+  protected final ChangeIndex index;
 
-  FuzzyTopicPredicate(String topic, ChangeIndex index) {
+  public FuzzyTopicPredicate(String topic, ChangeIndex index) {
     super(FUZZY_TOPIC, topic);
     this.index = index;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/GroupPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/GroupPredicate.java
index 54e1c977a6..d2645dcf5b 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/GroupPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/GroupPredicate.java
@@ -19,8 +19,8 @@ import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 import java.util.List;
 
-class GroupPredicate extends ChangeIndexPredicate {
-  GroupPredicate(String group) {
+public class GroupPredicate extends ChangeIndexPredicate {
+  public GroupPredicate(String group) {
     super(ChangeField.GROUP, group);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasDraftByPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasDraftByPredicate.java
index 244589cb7c..e422b74418 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasDraftByPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasDraftByPredicate.java
@@ -18,10 +18,10 @@ import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class HasDraftByPredicate extends ChangeIndexPredicate {
-  private final Account.Id accountId;
+public class HasDraftByPredicate extends ChangeIndexPredicate {
+  protected final Account.Id accountId;
 
-  HasDraftByPredicate(Account.Id accountId) {
+  public HasDraftByPredicate(Account.Id accountId) {
     super(ChangeField.DRAFTBY, accountId.toString());
     this.accountId = accountId;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasStarsPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasStarsPredicate.java
index eb3a13794e..b17fffd0b3 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasStarsPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HasStarsPredicate.java
@@ -19,9 +19,9 @@ import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
 public class HasStarsPredicate extends ChangeIndexPredicate {
-  private final Account.Id accountId;
+  protected final Account.Id accountId;
 
-  HasStarsPredicate(Account.Id accountId) {
+  public HasStarsPredicate(Account.Id accountId) {
     super(ChangeField.STARBY, accountId.toString());
     this.accountId = accountId;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HashtagPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HashtagPredicate.java
index 4fd4156c9c..a348d48f91 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HashtagPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/HashtagPredicate.java
@@ -18,8 +18,8 @@ import com.google.gerrit.server.change.HashtagsUtil;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class HashtagPredicate extends ChangeIndexPredicate {
-  HashtagPredicate(String hashtag) {
+public class HashtagPredicate extends ChangeIndexPredicate {
+  public HashtagPredicate(String hashtag) {
     super(ChangeField.HASHTAG, HashtagsUtil.cleanupHashtag(hashtag));
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsMergePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsMergePredicate.java
index 50e5bd9e43..28fb7cfcab 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsMergePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsMergePredicate.java
@@ -24,7 +24,7 @@ import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
 
 public class IsMergePredicate extends ChangeOperatorPredicate {
-  private final Arguments args;
+  protected final Arguments args;
 
   public IsMergePredicate(Arguments args, String value) {
     super(ChangeQueryBuilder.FIELD_MERGE, value);
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsReviewedPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsReviewedPredicate.java
index 92de09a9d9..8b6c8e699b 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsReviewedPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsReviewedPredicate.java
@@ -25,14 +25,14 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 
-class IsReviewedPredicate extends ChangeIndexPredicate {
-  private static final Account.Id NOT_REVIEWED = new Account.Id(ChangeField.NOT_REVIEWED);
+public class IsReviewedPredicate extends ChangeIndexPredicate {
+  protected static final Account.Id NOT_REVIEWED = new Account.Id(ChangeField.NOT_REVIEWED);
 
-  static Predicate<ChangeData> create() {
+  public static Predicate<ChangeData> create() {
     return Predicate.not(new IsReviewedPredicate(NOT_REVIEWED));
   }
 
-  static Predicate<ChangeData> create(Collection<Account.Id> ids) {
+  public static Predicate<ChangeData> create(Collection<Account.Id> ids) {
     List<Predicate<ChangeData>> predicates = new ArrayList<>(ids.size());
     for (Account.Id id : ids) {
       predicates.add(new IsReviewedPredicate(id));
@@ -40,7 +40,7 @@ class IsReviewedPredicate extends ChangeIndexPredicate {
     return Predicate.or(predicates);
   }
 
-  private final Account.Id id;
+  protected final Account.Id id;
 
   private IsReviewedPredicate(Account.Id id) {
     super(REVIEWEDBY, Integer.toString(id.get()));
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsUnresolvedPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsUnresolvedPredicate.java
index 17a63471c2..e9b2899208 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsUnresolvedPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsUnresolvedPredicate.java
@@ -19,11 +19,11 @@ import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
 public class IsUnresolvedPredicate extends IntegerRangeChangePredicate {
-  IsUnresolvedPredicate() throws QueryParseException {
+  public IsUnresolvedPredicate() throws QueryParseException {
     this(">0");
   }
 
-  IsUnresolvedPredicate(String value) throws QueryParseException {
+  public IsUnresolvedPredicate(String value) throws QueryParseException {
     super(ChangeField.UNRESOLVED_COMMENT_COUNT, value);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsWatchedByPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsWatchedByPredicate.java
index dda834b98f..a1a5070f57 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsWatchedByPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/IsWatchedByPredicate.java
@@ -26,23 +26,23 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
-class IsWatchedByPredicate extends AndPredicate<ChangeData> {
-  private static String describe(CurrentUser user) {
+public class IsWatchedByPredicate extends AndPredicate<ChangeData> {
+  protected static String describe(CurrentUser user) {
     if (user.isIdentifiedUser()) {
       return user.getAccountId().toString();
     }
     return user.toString();
   }
 
-  private final CurrentUser user;
+  protected final CurrentUser user;
 
-  IsWatchedByPredicate(ChangeQueryBuilder.Arguments args, boolean checkIsVisible)
+  public IsWatchedByPredicate(ChangeQueryBuilder.Arguments args, boolean checkIsVisible)
       throws QueryParseException {
     super(filters(args, checkIsVisible));
     this.user = args.getUser();
   }
 
-  private static List<Predicate<ChangeData>> filters(
+  protected static List<Predicate<ChangeData>> filters(
       ChangeQueryBuilder.Arguments args, boolean checkIsVisible) throws QueryParseException {
     List<Predicate<ChangeData>> r = new ArrayList<>();
     ChangeQueryBuilder builder = new ChangeQueryBuilder(args);
@@ -89,7 +89,7 @@ class IsWatchedByPredicate extends AndPredicate<ChangeData> {
     }
   }
 
-  private static Collection<ProjectWatchKey> getWatches(ChangeQueryBuilder.Arguments args)
+  protected static Collection<ProjectWatchKey> getWatches(ChangeQueryBuilder.Arguments args)
       throws QueryParseException {
     CurrentUser user = args.getUser();
     if (user.isIdentifiedUser()) {
@@ -98,7 +98,7 @@ class IsWatchedByPredicate extends AndPredicate<ChangeData> {
     return Collections.<ProjectWatchKey>emptySet();
   }
 
-  private static List<Predicate<ChangeData>> none() {
+  protected static List<Predicate<ChangeData>> none() {
     Predicate<ChangeData> any = any();
     return ImmutableList.of(not(any));
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LabelPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LabelPredicate.java
index 3fe6a6f287..bd342d79e7 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LabelPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LabelPredicate.java
@@ -33,19 +33,19 @@ import java.util.List;
 import java.util.Set;
 
 public class LabelPredicate extends OrPredicate<ChangeData> {
-  private static final int MAX_LABEL_VALUE = 4;
+  protected static final int MAX_LABEL_VALUE = 4;
 
-  static class Args {
-    final ProjectCache projectCache;
-    final PermissionBackend permissionBackend;
-    final ChangeControl.GenericFactory ccFactory;
-    final IdentifiedUser.GenericFactory userFactory;
-    final Provider<ReviewDb> dbProvider;
-    final String value;
-    final Set<Account.Id> accounts;
-    final AccountGroup.UUID group;
+  protected static class Args {
+    protected final ProjectCache projectCache;
+    protected final PermissionBackend permissionBackend;
+    protected final ChangeControl.GenericFactory ccFactory;
+    protected final IdentifiedUser.GenericFactory userFactory;
+    protected final Provider<ReviewDb> dbProvider;
+    protected final String value;
+    protected final Set<Account.Id> accounts;
+    protected final AccountGroup.UUID group;
 
-    private Args(
+    protected Args(
         ProjectCache projectCache,
         PermissionBackend permissionBackend,
         ChangeControl.GenericFactory ccFactory,
@@ -65,21 +65,21 @@ public class LabelPredicate extends OrPredicate<ChangeData> {
     }
   }
 
-  private static class Parsed {
-    private final String label;
-    private final String test;
-    private final int expVal;
+  protected static class Parsed {
+    protected final String label;
+    protected final String test;
+    protected final int expVal;
 
-    private Parsed(String label, String test, int expVal) {
+    protected Parsed(String label, String test, int expVal) {
       this.label = label;
       this.test = test;
       this.expVal = expVal;
     }
   }
 
-  private final String value;
+  protected final String value;
 
-  LabelPredicate(
+  public LabelPredicate(
       ChangeQueryBuilder.Arguments a,
       String value,
       Set<Account.Id> accounts,
@@ -98,7 +98,7 @@ public class LabelPredicate extends OrPredicate<ChangeData> {
     this.value = value;
   }
 
-  private static List<Predicate<ChangeData>> predicates(Args args) {
+  protected static List<Predicate<ChangeData>> predicates(Args args) {
     String v = args.value;
     Parsed parsed = null;
 
@@ -138,14 +138,14 @@ public class LabelPredicate extends OrPredicate<ChangeData> {
     return r;
   }
 
-  private static Predicate<ChangeData> onePredicate(Args args, String label, int expVal) {
+  protected static Predicate<ChangeData> onePredicate(Args args, String label, int expVal) {
     if (expVal != 0) {
       return equalsLabelPredicate(args, label, expVal);
     }
     return noLabelQuery(args, label);
   }
 
-  private static Predicate<ChangeData> noLabelQuery(Args args, String label) {
+  protected static Predicate<ChangeData> noLabelQuery(Args args, String label) {
     List<Predicate<ChangeData>> r = Lists.newArrayListWithCapacity(2 * MAX_LABEL_VALUE);
     for (int i = 1; i <= MAX_LABEL_VALUE; i++) {
       r.add(equalsLabelPredicate(args, label, i));
@@ -154,7 +154,7 @@ public class LabelPredicate extends OrPredicate<ChangeData> {
     return not(or(r));
   }
 
-  private static Predicate<ChangeData> equalsLabelPredicate(Args args, String label, int expVal) {
+  protected static Predicate<ChangeData> equalsLabelPredicate(Args args, String label, int expVal) {
     if (args.accounts == null || args.accounts.isEmpty()) {
       return new EqualsLabelPredicate(args, label, expVal, null);
     }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LegacyChangeIdPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LegacyChangeIdPredicate.java
index f7f98d5cdb..7cc8b31f64 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LegacyChangeIdPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/LegacyChangeIdPredicate.java
@@ -20,7 +20,7 @@ import com.google.gerrit.reviewdb.client.Change;
 
 /** Predicate over change number (aka legacy ID or Change.Id). */
 public class LegacyChangeIdPredicate extends ChangeIndexPredicate {
-  private final Change.Id id;
+  protected final Change.Id id;
 
   public LegacyChangeIdPredicate(Change.Id id) {
     super(LEGACY_ID, ChangeQueryBuilder.FIELD_CHANGE, id.toString());
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/MessagePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/MessagePredicate.java
index 9e525c267c..92d1ed3626 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/MessagePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/MessagePredicate.java
@@ -22,10 +22,10 @@ import com.google.gerrit.server.query.QueryParseException;
 import com.google.gwtorm.server.OrmException;
 
 /** Predicate to match changes that contains specified text in commit messages body. */
-class MessagePredicate extends ChangeIndexPredicate {
-  private final ChangeIndex index;
+public class MessagePredicate extends ChangeIndexPredicate {
+  protected final ChangeIndex index;
 
-  MessagePredicate(ChangeIndex index, String value) {
+  public MessagePredicate(ChangeIndex index, String value) {
     super(ChangeField.COMMIT_MESSAGE, value);
     this.index = index;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerPredicate.java
index dfaac08656..5fd1ca05c2 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerPredicate.java
@@ -19,15 +19,15 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class OwnerPredicate extends ChangeIndexPredicate {
-  private final Account.Id id;
+public class OwnerPredicate extends ChangeIndexPredicate {
+  protected final Account.Id id;
 
-  OwnerPredicate(Account.Id id) {
+  public OwnerPredicate(Account.Id id) {
     super(ChangeField.OWNER, id.toString());
     this.id = id;
   }
 
-  Account.Id getAccountId() {
+  protected Account.Id getAccountId() {
     return id;
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerinPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerinPredicate.java
index f3239afc81..f828970308 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerinPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/OwnerinPredicate.java
@@ -19,17 +19,17 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gwtorm.server.OrmException;
 
-class OwnerinPredicate extends ChangeOperatorPredicate {
-  private final IdentifiedUser.GenericFactory userFactory;
-  private final AccountGroup.UUID uuid;
+public class OwnerinPredicate extends ChangeOperatorPredicate {
+  protected final IdentifiedUser.GenericFactory userFactory;
+  protected final AccountGroup.UUID uuid;
 
-  OwnerinPredicate(IdentifiedUser.GenericFactory userFactory, AccountGroup.UUID uuid) {
+  public OwnerinPredicate(IdentifiedUser.GenericFactory userFactory, AccountGroup.UUID uuid) {
     super(ChangeQueryBuilder.FIELD_OWNERIN, uuid.toString());
     this.userFactory = userFactory;
     this.uuid = uuid;
   }
 
-  AccountGroup.UUID getAccountGroupUUID() {
+  protected AccountGroup.UUID getAccountGroupUUID() {
     return uuid;
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ParentProjectPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ParentProjectPredicate.java
index d3a3f20f99..64a2fa6045 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ParentProjectPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ParentProjectPredicate.java
@@ -28,10 +28,10 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
-class ParentProjectPredicate extends OrPredicate<ChangeData> {
-  private final String value;
+public class ParentProjectPredicate extends OrPredicate<ChangeData> {
+  protected final String value;
 
-  ParentProjectPredicate(
+  public ParentProjectPredicate(
       ProjectCache projectCache,
       Provider<ListChildProjects> listChildProjects,
       Provider<CurrentUser> self,
@@ -40,7 +40,7 @@ class ParentProjectPredicate extends OrPredicate<ChangeData> {
     this.value = value;
   }
 
-  private static List<Predicate<ChangeData>> predicates(
+  protected static List<Predicate<ChangeData>> predicates(
       ProjectCache projectCache,
       Provider<ListChildProjects> listChildProjects,
       Provider<CurrentUser> self,
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPredicate.java
index 644870dd42..ef25ddbaf1 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPredicate.java
@@ -19,12 +19,12 @@ import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class ProjectPredicate extends ChangeIndexPredicate {
-  ProjectPredicate(String id) {
+public class ProjectPredicate extends ChangeIndexPredicate {
+  public ProjectPredicate(String id) {
     super(ChangeField.PROJECT, id);
   }
 
-  Project.NameKey getValueKey() {
+  protected Project.NameKey getValueKey() {
     return new Project.NameKey(getValue());
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPrefixPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPrefixPredicate.java
index 4c06d1b758..28b1302d15 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPrefixPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ProjectPrefixPredicate.java
@@ -18,8 +18,8 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class ProjectPrefixPredicate extends ChangeIndexPredicate {
-  ProjectPrefixPredicate(String prefix) {
+public class ProjectPrefixPredicate extends ChangeIndexPredicate {
+  public ProjectPrefixPredicate(String prefix) {
     super(ChangeField.PROJECTS, prefix);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RefPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RefPredicate.java
index 491aed963e..b8bece9c0f 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RefPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RefPredicate.java
@@ -18,8 +18,8 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class RefPredicate extends ChangeIndexPredicate {
-  RefPredicate(String ref) {
+public class RefPredicate extends ChangeIndexPredicate {
+  public RefPredicate(String ref) {
     super(ChangeField.REF, ref);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexPathPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexPathPredicate.java
index 5b9774ce99..ca21247ac7 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexPathPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexPathPredicate.java
@@ -19,8 +19,8 @@ import com.google.gerrit.server.util.RegexListSearcher;
 import com.google.gwtorm.server.OrmException;
 import java.util.List;
 
-class RegexPathPredicate extends ChangeRegexPredicate {
-  RegexPathPredicate(String re) {
+public class RegexPathPredicate extends ChangeRegexPredicate {
+  public RegexPathPredicate(String re) {
     super(ChangeField.PATH, re);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexProjectPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexProjectPredicate.java
index 1284e8874c..cf78c576fb 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexProjectPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexProjectPredicate.java
@@ -21,10 +21,10 @@ import com.google.gwtorm.server.OrmException;
 import dk.brics.automaton.RegExp;
 import dk.brics.automaton.RunAutomaton;
 
-class RegexProjectPredicate extends ChangeRegexPredicate {
-  private final RunAutomaton pattern;
+public class RegexProjectPredicate extends ChangeRegexPredicate {
+  protected final RunAutomaton pattern;
 
-  RegexProjectPredicate(String re) {
+  public RegexProjectPredicate(String re) {
     super(ChangeField.PROJECT, re);
 
     if (re.startsWith("^")) {
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexRefPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexRefPredicate.java
index 671d4cc710..ac7af9ba0e 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexRefPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexRefPredicate.java
@@ -20,10 +20,10 @@ import com.google.gwtorm.server.OrmException;
 import dk.brics.automaton.RegExp;
 import dk.brics.automaton.RunAutomaton;
 
-class RegexRefPredicate extends ChangeRegexPredicate {
-  private final RunAutomaton pattern;
+public class RegexRefPredicate extends ChangeRegexPredicate {
+  protected final RunAutomaton pattern;
 
-  RegexRefPredicate(String re) {
+  public RegexRefPredicate(String re) {
     super(ChangeField.REF, re);
 
     if (re.startsWith("^")) {
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexTopicPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexTopicPredicate.java
index a4ba05935f..8a9f8cdda8 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexTopicPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/RegexTopicPredicate.java
@@ -21,10 +21,10 @@ import com.google.gwtorm.server.OrmException;
 import dk.brics.automaton.RegExp;
 import dk.brics.automaton.RunAutomaton;
 
-class RegexTopicPredicate extends ChangeRegexPredicate {
-  private final RunAutomaton pattern;
+public class RegexTopicPredicate extends ChangeRegexPredicate {
+  protected final RunAutomaton pattern;
 
-  RegexTopicPredicate(String re) {
+  public RegexTopicPredicate(String re) {
     super(EXACT_TOPIC, re);
 
     if (re.startsWith("^")) {
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerPredicate.java
index 5b8649476d..f3a86191ec 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerPredicate.java
@@ -25,14 +25,14 @@ import com.google.gerrit.server.query.change.ChangeQueryBuilder.Arguments;
 import com.google.gwtorm.server.OrmException;
 import java.util.stream.Stream;
 
-class ReviewerPredicate extends ChangeIndexPredicate {
-  static Predicate<ChangeData> forState(
+public class ReviewerPredicate extends ChangeIndexPredicate {
+  protected static Predicate<ChangeData> forState(
       Arguments args, Account.Id id, ReviewerStateInternal state) {
     checkArgument(state != ReviewerStateInternal.REMOVED, "can't query by removed reviewer");
     return create(args, new ReviewerPredicate(state, id));
   }
 
-  static Predicate<ChangeData> reviewer(Arguments args, Account.Id id) {
+  protected static Predicate<ChangeData> reviewer(Arguments args, Account.Id id) {
     Predicate<ChangeData> p;
     if (args.notesMigration.readChanges()) {
       // With NoteDb, Reviewer/CC are clearly distinct states, so only choose reviewer.
@@ -45,14 +45,14 @@ class ReviewerPredicate extends ChangeIndexPredicate {
     return create(args, p);
   }
 
-  static Predicate<ChangeData> cc(Arguments args, Account.Id id) {
+  protected static Predicate<ChangeData> cc(Arguments args, Account.Id id) {
     // As noted above, CC is nebulous without NoteDb, but it certainly doesn't make sense to return
     // Reviewers for cc:foo. Most likely this will just not match anything, but let the index sort
     // it out.
     return create(args, new ReviewerPredicate(ReviewerStateInternal.CC, id));
   }
 
-  private static Predicate<ChangeData> anyReviewerState(Account.Id id) {
+  protected static Predicate<ChangeData> anyReviewerState(Account.Id id) {
     return Predicate.or(
         Stream.of(ReviewerStateInternal.values())
             .filter(s -> s != ReviewerStateInternal.REMOVED)
@@ -60,8 +60,8 @@ class ReviewerPredicate extends ChangeIndexPredicate {
             .collect(toList()));
   }
 
-  private final ReviewerStateInternal state;
-  private final Account.Id id;
+  protected final ReviewerStateInternal state;
+  protected final Account.Id id;
 
   private ReviewerPredicate(ReviewerStateInternal state, Account.Id id) {
     super(ChangeField.REVIEWER, ChangeField.getReviewerFieldValue(state, id));
@@ -69,7 +69,7 @@ class ReviewerPredicate extends ChangeIndexPredicate {
     this.id = id;
   }
 
-  Account.Id getAccountId() {
+  protected Account.Id getAccountId() {
     return id;
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerinPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerinPredicate.java
index 63e7859824..df28de32a0 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerinPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ReviewerinPredicate.java
@@ -19,17 +19,17 @@ import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gwtorm.server.OrmException;
 
-class ReviewerinPredicate extends ChangeOperatorPredicate {
-  private final IdentifiedUser.GenericFactory userFactory;
-  private final AccountGroup.UUID uuid;
+public class ReviewerinPredicate extends ChangeOperatorPredicate {
+  protected final IdentifiedUser.GenericFactory userFactory;
+  protected final AccountGroup.UUID uuid;
 
-  ReviewerinPredicate(IdentifiedUser.GenericFactory userFactory, AccountGroup.UUID uuid) {
+  public ReviewerinPredicate(IdentifiedUser.GenericFactory userFactory, AccountGroup.UUID uuid) {
     super(ChangeQueryBuilder.FIELD_REVIEWERIN, uuid.toString());
     this.userFactory = userFactory;
     this.uuid = uuid;
   }
 
-  AccountGroup.UUID getAccountGroupUUID() {
+  protected AccountGroup.UUID getAccountGroupUUID() {
     return uuid;
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/StarPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/StarPredicate.java
index 98965bf604..12d4753d8a 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/StarPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/StarPredicate.java
@@ -20,10 +20,10 @@ import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
 public class StarPredicate extends ChangeIndexPredicate {
-  private final Account.Id accountId;
-  private final String label;
+  protected final Account.Id accountId;
+  protected final String label;
 
-  StarPredicate(Account.Id accountId, String label) {
+  public StarPredicate(Account.Id accountId, String label) {
     super(ChangeField.STAR, StarredChangesUtil.StarField.create(accountId, label).toString());
     this.accountId = accountId;
     this.label = label;
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmissionIdPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmissionIdPredicate.java
index d8d5258e35..5fdeb68da6 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmissionIdPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmissionIdPredicate.java
@@ -18,9 +18,8 @@ import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class SubmissionIdPredicate extends ChangeIndexPredicate {
-
-  SubmissionIdPredicate(String changeSet) {
+public class SubmissionIdPredicate extends ChangeIndexPredicate {
+  public SubmissionIdPredicate(String changeSet) {
     super(ChangeField.SUBMISSIONID, changeSet);
   }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmitRecordPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmitRecordPredicate.java
index 5b01ea2a05..81d64e0e94 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmitRecordPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmitRecordPredicate.java
@@ -23,8 +23,8 @@ import com.google.gerrit.server.query.Predicate;
 import com.google.gwtorm.server.OrmException;
 import java.util.Set;
 
-class SubmitRecordPredicate extends ChangeIndexPredicate {
-  static Predicate<ChangeData> create(
+public class SubmitRecordPredicate extends ChangeIndexPredicate {
+  public static Predicate<ChangeData> create(
       String label, SubmitRecord.Label.Status status, Set<Account.Id> accounts) {
     String lowerLabel = label.toLowerCase();
     if (accounts == null || accounts.isEmpty()) {
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmittablePredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmittablePredicate.java
index 0812c6a39b..df78315bd5 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmittablePredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/SubmittablePredicate.java
@@ -18,10 +18,10 @@ import com.google.gerrit.common.data.SubmitRecord;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gwtorm.server.OrmException;
 
-class SubmittablePredicate extends ChangeIndexPredicate {
-  private final SubmitRecord.Status status;
+public class SubmittablePredicate extends ChangeIndexPredicate {
+  protected final SubmitRecord.Status status;
 
-  SubmittablePredicate(SubmitRecord.Status status) {
+  public SubmittablePredicate(SubmitRecord.Status status) {
     super(ChangeField.SUBMIT_RECORD, status.name());
     this.status = status;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/TrackingIdPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/TrackingIdPredicate.java
index afaea5c9ab..6a5f260b87 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/TrackingIdPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/TrackingIdPredicate.java
@@ -24,12 +24,12 @@ import org.eclipse.jgit.revwalk.FooterLine;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-class TrackingIdPredicate extends ChangeIndexPredicate {
+public class TrackingIdPredicate extends ChangeIndexPredicate {
   private static final Logger log = LoggerFactory.getLogger(TrackingIdPredicate.class);
 
-  private final TrackingFooters trackingFooters;
+  protected final TrackingFooters trackingFooters;
 
-  TrackingIdPredicate(TrackingFooters trackingFooters, String trackingId) {
+  public TrackingIdPredicate(TrackingFooters trackingFooters, String trackingId) {
     super(ChangeField.TR, trackingId);
     this.trackingFooters = trackingFooters;
   }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/group/GroupIsVisibleToPredicate.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/group/GroupIsVisibleToPredicate.java
index 8f7294568d..3ac9c39b58 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/group/GroupIsVisibleToPredicate.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/group/GroupIsVisibleToPredicate.java
@@ -23,10 +23,11 @@ import com.google.gerrit.server.query.account.AccountQueryBuilder;
 import com.google.gwtorm.server.OrmException;
 
 public class GroupIsVisibleToPredicate extends IsVisibleToPredicate<AccountGroup> {
-  private final GroupControl.GenericFactory groupControlFactory;
-  private final CurrentUser user;
+  protected final GroupControl.GenericFactory groupControlFactory;
+  protected final CurrentUser user;
 
-  GroupIsVisibleToPredicate(GroupControl.GenericFactory groupControlFactory, CurrentUser user) {
+  public GroupIsVisibleToPredicate(
+      GroupControl.GenericFactory groupControlFactory, CurrentUser user) {
     super(AccountQueryBuilder.FIELD_VISIBLETO, describe(user));
     this.groupControlFactory = groupControlFactory;
     this.user = user;