Merge branch 'stable-2.15'

* stable-2.15:
  ElasticIndexVersionDiscovery: Convert to Java stream API
  ElasticVersionManager: Use correct configuration value for prefix
  Elasticsearch: Refactor generation of bulk requests
  Rename AbstractReindexIT to AbstractReindexTests
  ElasticReindexIT: Use @ConfigSuite.Default instead of @ConfigSuite.Config

Change-Id: Iacd3f2db3728a9c1936170b575016973bf0336d9

java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java

@@ -17,26 +17,22 @@ package com.google.gerrit.elasticsearch;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES;
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static java.util.stream.Collectors.toList;
 import static org.apache.commons.codec.binary.Base64.decodeBase64;
 
 import com.google.common.base.Strings;
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.FluentIterable;
-import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Streams;
 import com.google.common.io.CharStreams;
 import com.google.gerrit.elasticsearch.builders.QueryBuilder;
 import com.google.gerrit.elasticsearch.builders.SearchSourceBuilder;
-import com.google.gerrit.elasticsearch.builders.XContentBuilder;
+import com.google.gerrit.elasticsearch.bulk.DeleteRequest;
 import com.google.gerrit.index.FieldDef;
 import com.google.gerrit.index.FieldType;
 import com.google.gerrit.index.Index;
 import com.google.gerrit.index.QueryOptions;
 import com.google.gerrit.index.Schema;
-import com.google.gerrit.index.Schema.Values;
 import com.google.gerrit.index.query.DataSource;
 import com.google.gerrit.index.query.FieldBundle;
 import com.google.gerrit.index.query.Predicate;
@@ -71,10 +67,7 @@ import org.apache.commons.codec.binary.Base64;
 import org.apache.http.HttpEntity;
 import org.apache.http.HttpStatus;
 import org.apache.http.StatusLine;
-import org.apache.http.client.methods.HttpDelete;
-import org.apache.http.client.methods.HttpHead;
 import org.apache.http.client.methods.HttpPost;
-import org.apache.http.client.methods.HttpPut;
 import org.apache.http.entity.ContentType;
 import org.apache.http.nio.entity.NStringEntity;
 import org.eclipse.jgit.lib.Config;
@@ -87,9 +80,7 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
   private static final Logger log = LoggerFactory.getLogger(AbstractElasticIndex.class);
 
   protected static final String BULK = "_bulk";
-  protected static final String DELETE = "delete";
   protected static final String IGNORE_UNMAPPED = "ignore_unmapped";
-  protected static final String INDEX = "index";
   protected static final String ORDER = "order";
   protected static final String SEARCH = "_search";
 
@@ -167,7 +158,7 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
   @Override
   public void delete(K c) throws IOException {
     String uri = getURI(indexNameRaw, BULK);
-    Response response = performRequest(HttpPost.METHOD_NAME, addActions(c), uri, getRefreshParam());
+    Response response = postRequest(addActions(c), uri, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       throw new IOException(
@@ -178,10 +169,10 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
   @Override
   public void deleteAll() throws IOException {
     // Delete the index, if it exists.
-    Response response = client.performRequest(HttpHead.METHOD_NAME, indexName);
+    Response response = client.performRequest("HEAD", indexName);
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode == HttpStatus.SC_OK) {
-      response = client.performRequest(HttpDelete.METHOD_NAME, indexName);
+      response = client.performRequest("DELETE", indexName);
       statusCode = response.getStatusLine().getStatusCode();
       if (statusCode != HttpStatus.SC_OK) {
         throw new IOException(
@@ -190,8 +181,7 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
     }
 
     // Recreate the index.
-    response =
-        performRequest(HttpPut.METHOD_NAME, getMappings(), indexName, Collections.emptyMap());
+    response = performRequest("PUT", getMappings(), indexName, Collections.emptyMap());
     statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       String error = String.format("Failed to create index %s: %s", indexName, statusCode);
@@ -207,33 +197,7 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
 
   protected String delete(String type, K c) {
     String id = c.toString();
-    return toAction(type, id, DELETE);
-  }
-
-  private static boolean shouldAddElement(Object element) {
-    return !(element instanceof String) || !((String) element).isEmpty();
-  }
-
-  protected String toDoc(V v) throws IOException {
-    try (XContentBuilder closeable = new XContentBuilder()) {
-      XContentBuilder builder = closeable.startObject();
-      for (Values<V> values : schema.buildFields(v)) {
-        String name = values.getField().getName();
-        if (values.getField().isRepeatable()) {
-          builder.field(
-              name,
-              Streams.stream(values.getValues())
-                  .filter(AbstractElasticIndex::shouldAddElement)
-                  .collect(toList()));
-        } else {
-          Object element = Iterables.getOnlyElement(values.getValues(), "");
-          if (shouldAddElement(element)) {
-            builder.field(name, element);
-          }
-        }
-      }
-      return builder.endObject().string() + System.lineSeparator();
-    }
+    return new DeleteRequest(id, indexNameRaw, type).toString();
   }
 
   protected abstract V fromDocument(JsonObject doc, Set<String> fields);
@@ -313,9 +277,15 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
     return encodedIndexName + "/" + encodedType + "/" + request;
   }
 
-  protected Response performRequest(
-      String method, String payload, String uri, Map<String, String> params) throws IOException {
-    HttpEntity entity = new NStringEntity(payload, ContentType.APPLICATION_JSON);
+  protected Response postRequest(Object payload, String uri, Map<String, String> params)
+      throws IOException {
+    return performRequest("POST", payload, uri, params);
+  }
+
+  private Response performRequest(
+      String method, Object payload, String uri, Map<String, String> params) throws IOException {
+    String payloadStr = payload instanceof String ? (String) payload : payload.toString();
+    HttpEntity entity = new NStringEntity(payloadStr, ContentType.APPLICATION_JSON);
     return client.performRequest(method, uri, params, entity);
   }
 

java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java

@@ -18,6 +18,9 @@ import static com.google.gerrit.server.index.account.AccountField.ID;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.gerrit.elasticsearch.ElasticMapping.MappingProperties;
+import com.google.gerrit.elasticsearch.bulk.BulkRequest;
+import com.google.gerrit.elasticsearch.bulk.IndexRequest;
+import com.google.gerrit.elasticsearch.bulk.UpdateRequest;
 import com.google.gerrit.index.QueryOptions;
 import com.google.gerrit.index.Schema;
 import com.google.gerrit.index.query.DataSource;
@@ -40,7 +43,6 @@ import com.google.inject.assistedinject.Assisted;
 import java.io.IOException;
 import java.util.Set;
 import org.apache.http.HttpStatus;
-import org.apache.http.client.methods.HttpPost;
 import org.eclipse.jgit.lib.Config;
 import org.elasticsearch.client.Response;
 
@@ -58,6 +60,7 @@ public class ElasticAccountIndex extends AbstractElasticIndex<Account.Id, Accoun
 
   private final AccountMapping mapping;
   private final Provider<AccountCache> accountCache;
+  private final Schema<AccountState> schema;
 
   @Inject
   ElasticAccountIndex(
@@ -69,15 +72,16 @@ public class ElasticAccountIndex extends AbstractElasticIndex<Account.Id, Accoun
     super(cfg, sitePaths, schema, clientBuilder, ACCOUNTS);
     this.accountCache = accountCache;
     this.mapping = new AccountMapping(schema);
+    this.schema = schema;
   }
 
   @Override
   public void replace(AccountState as) throws IOException {
-    String bulk = toAction(ACCOUNTS, getId(as), INDEX);
-    bulk += toDoc(as);
+    BulkRequest bulk =
+        new IndexRequest(getId(as), indexName, ACCOUNTS).add(new UpdateRequest<>(schema, as));
 
     String uri = getURI(ACCOUNTS, BULK);
-    Response response = performRequest(HttpPost.METHOD_NAME, bulk, uri, getRefreshParam());
+    Response response = postRequest(bulk, uri, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       throw new IOException(

java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java

@@ -32,6 +32,10 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Sets;
 import com.google.gerrit.elasticsearch.ElasticMapping.MappingProperties;
+import com.google.gerrit.elasticsearch.bulk.BulkRequest;
+import com.google.gerrit.elasticsearch.bulk.DeleteRequest;
+import com.google.gerrit.elasticsearch.bulk.IndexRequest;
+import com.google.gerrit.elasticsearch.bulk.UpdateRequest;
 import com.google.gerrit.index.QueryOptions;
 import com.google.gerrit.index.Schema;
 import com.google.gerrit.index.query.DataSource;
@@ -67,7 +71,6 @@ import java.util.Optional;
 import java.util.Set;
 import org.apache.commons.codec.binary.Base64;
 import org.apache.http.HttpStatus;
-import org.apache.http.client.methods.HttpPost;
 import org.eclipse.jgit.lib.Config;
 import org.elasticsearch.client.Response;
 
@@ -92,6 +95,7 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
   private final ChangeMapping mapping;
   private final Provider<ReviewDb> db;
   private final ChangeData.Factory changeDataFactory;
+  private final Schema<ChangeData> schema;
 
   @Inject
   ElasticChangeIndex(
@@ -104,6 +108,7 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
     super(cfg, sitePaths, schema, clientBuilder, CHANGES);
     this.db = db;
     this.changeDataFactory = changeDataFactory;
+    this.schema = schema;
     mapping = new ChangeMapping(schema);
   }
 
@@ -124,12 +129,13 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
       throw new IOException(e);
     }
 
-    String bulk = toAction(insertIndex, getId(cd), INDEX);
-    bulk += toDoc(cd);
-    bulk += toAction(deleteIndex, cd.getId().toString(), DELETE);
+    BulkRequest bulk =
+        new IndexRequest(getId(cd), indexName, insertIndex)
+            .add(new UpdateRequest<>(schema, cd))
+            .add(new DeleteRequest(cd.getId().toString(), indexName, deleteIndex));
 
     String uri = getURI(CHANGES, BULK);
-    Response response = performRequest(HttpPost.METHOD_NAME, bulk, uri, getRefreshParam());
+    Response response = postRequest(bulk, uri, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       throw new IOException(

java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java

@@ -16,6 +16,9 @@ package com.google.gerrit.elasticsearch;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.gerrit.elasticsearch.ElasticMapping.MappingProperties;
+import com.google.gerrit.elasticsearch.bulk.BulkRequest;
+import com.google.gerrit.elasticsearch.bulk.IndexRequest;
+import com.google.gerrit.elasticsearch.bulk.UpdateRequest;
 import com.google.gerrit.index.QueryOptions;
 import com.google.gerrit.index.Schema;
 import com.google.gerrit.index.query.DataSource;
@@ -38,7 +41,6 @@ import com.google.inject.assistedinject.Assisted;
 import java.io.IOException;
 import java.util.Set;
 import org.apache.http.HttpStatus;
-import org.apache.http.client.methods.HttpPost;
 import org.eclipse.jgit.lib.Config;
 import org.elasticsearch.client.Response;
 
@@ -56,6 +58,7 @@ public class ElasticGroupIndex extends AbstractElasticIndex<AccountGroup.UUID, I
 
   private final GroupMapping mapping;
   private final Provider<GroupCache> groupCache;
+  private final Schema<InternalGroup> schema;
 
   @Inject
   ElasticGroupIndex(
@@ -67,15 +70,16 @@ public class ElasticGroupIndex extends AbstractElasticIndex<AccountGroup.UUID, I
     super(cfg, sitePaths, schema, clientBuilder, GROUPS);
     this.groupCache = groupCache;
     this.mapping = new GroupMapping(schema);
+    this.schema = schema;
   }
 
   @Override
   public void replace(InternalGroup group) throws IOException {
-    String bulk = toAction(GROUPS, getId(group), INDEX);
-    bulk += toDoc(group);
+    BulkRequest bulk =
+        new IndexRequest(getId(group), indexName, GROUPS).add(new UpdateRequest<>(schema, group));
 
     String uri = getURI(GROUPS, BULK);
-    Response response = performRequest(HttpPost.METHOD_NAME, bulk, uri, getRefreshParam());
+    Response response = postRequest(bulk, uri, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       throw new IOException(

java/com/google/gerrit/elasticsearch/ElasticIndexVersionDiscovery.java

@@ -14,16 +14,14 @@
 
 package com.google.gerrit.elasticsearch;
 
-import com.google.gson.JsonElement;
-import com.google.gson.JsonObject;
+import static java.util.stream.Collectors.toList;
+
 import com.google.gson.JsonParser;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map.Entry;
 import org.apache.http.HttpStatus;
 import org.apache.http.client.methods.HttpGet;
 import org.elasticsearch.client.Response;
@@ -42,16 +40,14 @@ class ElasticIndexVersionDiscovery {
     String name = prefix + indexName + "_";
     Response response = client.performRequest(HttpGet.METHOD_NAME, name + "*/_aliases");
 
-    int statusCode = response.getStatusLine().getStatusCode();
-    if (statusCode == HttpStatus.SC_OK) {
-      String content = AbstractElasticIndex.getContent(response);
-      JsonObject object = new JsonParser().parse(content).getAsJsonObject();
-
-      List<String> versions = new ArrayList<>(object.size());
-      for (Entry<String, JsonElement> entry : object.entrySet()) {
-        versions.add(entry.getKey().replace(name, ""));
-      }
-      return versions;
+    if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
+      return new JsonParser()
+          .parse(AbstractElasticIndex.getContent(response))
+          .getAsJsonObject()
+          .entrySet()
+          .stream()
+          .map(e -> e.getKey().replace(name, ""))
+          .collect(toList());
     }
     return Collections.emptyList();
   }

java/com/google/gerrit/elasticsearch/ElasticProjectIndex.java

@@ -16,6 +16,9 @@ package com.google.gerrit.elasticsearch;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.gerrit.elasticsearch.ElasticMapping.MappingProperties;
+import com.google.gerrit.elasticsearch.bulk.BulkRequest;
+import com.google.gerrit.elasticsearch.bulk.IndexRequest;
+import com.google.gerrit.elasticsearch.bulk.UpdateRequest;
 import com.google.gerrit.index.QueryOptions;
 import com.google.gerrit.index.Schema;
 import com.google.gerrit.index.project.ProjectData;
@@ -38,7 +41,6 @@ import com.google.inject.assistedinject.Assisted;
 import java.io.IOException;
 import java.util.Set;
 import org.apache.http.HttpStatus;
-import org.apache.http.client.methods.HttpPost;
 import org.eclipse.jgit.lib.Config;
 import org.elasticsearch.client.Response;
 
@@ -56,6 +58,7 @@ public class ElasticProjectIndex extends AbstractElasticIndex<Project.NameKey, P
 
   private final ProjectMapping mapping;
   private final Provider<ProjectCache> projectCache;
+  private final Schema<ProjectData> schema;
 
   @Inject
   ElasticProjectIndex(
@@ -66,16 +69,18 @@ public class ElasticProjectIndex extends AbstractElasticIndex<Project.NameKey, P
       @Assisted Schema<ProjectData> schema) {
     super(cfg, sitePaths, schema, clientBuilder, PROJECTS);
     this.projectCache = projectCache;
+    this.schema = schema;
     this.mapping = new ProjectMapping(schema);
   }
 
   @Override
   public void replace(ProjectData projectState) throws IOException {
-    String bulk = toAction(PROJECTS, getId(projectState), INDEX);
-    bulk += toDoc(projectState);
+    BulkRequest bulk =
+        new IndexRequest(projectState.getProject().getName(), indexName, PROJECTS)
+            .add(new UpdateRequest<>(schema, projectState));
 
     String uri = getURI(PROJECTS, BULK);
-    Response response = performRequest(HttpPost.METHOD_NAME, bulk, uri, getRefreshParam());
+    Response response = postRequest(bulk, uri, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       throw new IOException(

java/com/google/gerrit/elasticsearch/ElasticVersionManager.java

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.elasticsearch;
 
-import com.google.common.base.MoreObjects;
+import com.google.common.base.Strings;
 import com.google.common.primitives.Ints;
 import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.index.Index;
@@ -50,7 +50,7 @@ public class ElasticVersionManager extends VersionManager {
       ElasticIndexVersionDiscovery versionDiscovery) {
     super(sitePaths, listeners, defs, VersionManager.getOnlineUpgrade(cfg));
     this.versionDiscovery = versionDiscovery;
-    prefix = MoreObjects.firstNonNull(cfg.getString("index", null, "prefix"), "gerrit");
+    prefix = Strings.nullToEmpty(cfg.getString("elasticsearch", null, "prefix"));
   }
 
   @Override

java/com/google/gerrit/elasticsearch/bulk/ActionRequest.java

@@ -0,0 +1,44 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.elasticsearch.bulk;
+
+import com.google.gson.JsonObject;
+
+abstract class ActionRequest extends BulkRequest {
+
+  private final String action;
+  private final String id;
+  private final String index;
+  private final String type;
+
+  protected ActionRequest(String action, String id, String index, String type) {
+    this.action = action;
+    this.id = id;
+    this.index = index;
+    this.type = type;
+  }
+
+  @Override
+  protected String getRequest() {
+    JsonObject properties = new JsonObject();
+    properties.addProperty("_id", id);
+    properties.addProperty("_index", index);
+    properties.addProperty("_type", type);
+
+    JsonObject jsonAction = new JsonObject();
+    jsonAction.add(action, properties);
+    return jsonAction.toString() + System.lineSeparator();
+  }
+}

java/com/google/gerrit/elasticsearch/bulk/BulkRequest.java

@@ -0,0 +1,43 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.elasticsearch.bulk;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public abstract class BulkRequest {
+
+  private final List<BulkRequest> requests = new ArrayList<>();
+
+  protected BulkRequest() {
+    add(this);
+  }
+
+  public BulkRequest add(BulkRequest request) {
+    requests.add(request);
+    return this;
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder builder = new StringBuilder();
+    for (BulkRequest request : requests) {
+      builder.append(request.getRequest());
+    }
+    return builder.toString();
+  }
+
+  protected abstract String getRequest();
+}

java/com/google/gerrit/elasticsearch/bulk/DeleteRequest.java

@@ -0,0 +1,22 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.elasticsearch.bulk;
+
+public class DeleteRequest extends ActionRequest {
+
+  public DeleteRequest(String id, String index, String type) {
+    super("delete", id, index, type);
+  }
+}

java/com/google/gerrit/elasticsearch/bulk/IndexRequest.java

@@ -0,0 +1,22 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.elasticsearch.bulk;
+
+public class IndexRequest extends ActionRequest {
+
+  public IndexRequest(String id, String index, String type) {
+    super("index", id, index, type);
+  }
+}

java/com/google/gerrit/elasticsearch/bulk/UpdateRequest.java

@@ -0,0 +1,64 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.elasticsearch.bulk;
+
+import static java.util.stream.Collectors.toList;
+
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Streams;
+import com.google.gerrit.elasticsearch.builders.XContentBuilder;
+import com.google.gerrit.index.Schema;
+import com.google.gerrit.index.Schema.Values;
+import java.io.IOException;
+
+public class UpdateRequest<V> extends BulkRequest {
+
+  private final Schema<V> schema;
+  private final V v;
+
+  public UpdateRequest(Schema<V> schema, V v) {
+    this.schema = schema;
+    this.v = v;
+  }
+
+  @Override
+  protected String getRequest() {
+    try (XContentBuilder closeable = new XContentBuilder()) {
+      XContentBuilder builder = closeable.startObject();
+      for (Values<V> values : schema.buildFields(v)) {
+        String name = values.getField().getName();
+        if (values.getField().isRepeatable()) {
+          builder.field(
+              name,
+              Streams.stream(values.getValues())
+                  .filter(e -> shouldAddElement(e))
+                  .collect(toList()));
+        } else {
+          Object element = Iterables.getOnlyElement(values.getValues(), "");
+          if (shouldAddElement(element)) {
+            builder.field(name, element);
+          }
+        }
+      }
+      return builder.endObject().string() + System.lineSeparator();
+    } catch (IOException e) {
+      return e.toString();
+    }
+  }
+
+  private boolean shouldAddElement(Object element) {
+    return !(element instanceof String) || !((String) element).isEmpty();
+  }
+}