Adds ToXContentFragment (#25771)

* Adds ToXContentFragment

This interface is meant for objects that implement `ToXContent` but are not complete objects. It is basically the opposite of `ToXContentObject`. It means that it will be easier to track the migration of classes over to the fragment/not fragment ToXContent model as it will be clear which classes are not migrated. When no classes directly implement `ToXContent` we can make `ToXContent` package private to be sure that all new classes must implement `ToXContentObject` or `ToXContentFragment`.

* review comments

* more review comments

* javadocs

* iter

* Adds tests

* iter

* adds toString test for aggs

* improves tests following review comments

* iter

* iter

core/src/main/java/org/elasticsearch/ElasticsearchException.java

@@ -28,7 +28,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.logging.LoggerMessageFormat;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.Index;
@@ -57,7 +57,7 @@ import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureFieldN
 /**
  * A base class for all elasticsearch exceptions.
  */
-public class ElasticsearchException extends RuntimeException implements ToXContent, Writeable {
+public class ElasticsearchException extends RuntimeException implements ToXContentFragment, Writeable {
 
     private static final Version UNKNOWN_VERSION_ADDED = Version.fromId(0);
 

core/src/main/java/org/elasticsearch/action/admin/cluster/allocation/ClusterAllocationExplanation.java

@@ -30,7 +30,7 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.shard.ShardId;
 
@@ -44,7 +44,7 @@ import static org.elasticsearch.cluster.routing.allocation.AbstractAllocationDec
  * or if it is not unassigned, then which nodes it could possibly be relocated to.
  * It is an immutable class.
  */
-public final class ClusterAllocationExplanation implements ToXContent, Writeable {
+public final class ClusterAllocationExplanation implements ToXContentObject, Writeable {
 
     private final ShardRouting shardRouting;
     private final DiscoveryNode currentNode;

core/src/main/java/org/elasticsearch/action/admin/cluster/shards/ClusterSearchShardsGroup.java

@@ -23,13 +23,13 @@ import org.elasticsearch.cluster.routing.ShardRouting;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.shard.ShardId;
 
 import java.io.IOException;
 
-public class ClusterSearchShardsGroup implements Streamable, ToXContent {
+public class ClusterSearchShardsGroup implements Streamable, ToXContentObject {
 
     private ShardId shardId;
     private ShardRouting[] shards;

core/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsIndices.java

@@ -21,8 +21,10 @@ package org.elasticsearch.action.admin.cluster.stats;
 
 import com.carrotsearch.hppc.ObjectObjectHashMap;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+
 import org.elasticsearch.action.admin.indices.stats.CommonStats;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.cache.query.QueryCacheStats;
 import org.elasticsearch.index.engine.SegmentsStats;
@@ -34,7 +36,7 @@ import org.elasticsearch.search.suggest.completion.CompletionStats;
 import java.io.IOException;
 import java.util.List;
 
-public class ClusterStatsIndices implements ToXContent {
+public class ClusterStatsIndices implements ToXContentFragment {
 
     private int indexCount;
     private ShardStats shards;

core/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsNodes.java

@@ -21,6 +21,7 @@ package org.elasticsearch.action.admin.cluster.stats;
 
 import com.carrotsearch.hppc.ObjectIntHashMap;
 import com.carrotsearch.hppc.cursors.ObjectIntCursor;
+
 import org.elasticsearch.Version;
 import org.elasticsearch.action.admin.cluster.node.info.NodeInfo;
 import org.elasticsearch.action.admin.cluster.node.stats.NodeStats;
@@ -32,6 +33,7 @@ import org.elasticsearch.common.transport.TransportAddress;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.monitor.fs.FsInfo;
 import org.elasticsearch.monitor.jvm.JvmInfo;
@@ -48,7 +50,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
 
-public class ClusterStatsNodes implements ToXContent {
+public class ClusterStatsNodes implements ToXContentFragment {
 
     private final Counts counts;
     private final Set<Version> versions;
@@ -169,7 +171,7 @@ public class ClusterStatsNodes implements ToXContent {
         return builder;
     }
 
-    public static class Counts implements ToXContent {
+    public static class Counts implements ToXContentFragment {
         static final String COORDINATING_ONLY = "coordinating_only";
 
         private final int total;
@@ -394,7 +396,7 @@ public class ClusterStatsNodes implements ToXContent {
         }
     }
 
-    public static class JvmStats implements ToXContent {
+    public static class JvmStats implements ToXContentFragment {
 
         private final ObjectIntHashMap<JvmVersion> versions;
         private final long threads;

core/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsResponse.java

@@ -25,7 +25,7 @@ import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.health.ClusterHealthStatus;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 
@@ -33,7 +33,7 @@ import java.io.IOException;
 import java.util.List;
 import java.util.Locale;
 
-public class ClusterStatsResponse extends BaseNodesResponse<ClusterStatsNodeResponse> implements ToXContent {
+public class ClusterStatsResponse extends BaseNodesResponse<ClusterStatsNodeResponse> implements ToXContentFragment {
 
     ClusterStatsNodes nodesStats;
     ClusterStatsIndices indicesStats;

core/src/main/java/org/elasticsearch/action/admin/cluster/storedscripts/GetStoredScriptResponse.java

@@ -23,13 +23,13 @@ import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionResponse;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.script.StoredScriptSource;
 
 import java.io.IOException;
 
-public class GetStoredScriptResponse extends ActionResponse implements ToXContent {
+public class GetStoredScriptResponse extends ActionResponse implements ToXContentObject {
 
     private StoredScriptSource source;
 

core/src/main/java/org/elasticsearch/action/admin/indices/analyze/DetailAnalyzeResponse.java

@@ -24,12 +24,13 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class DetailAnalyzeResponse implements Streamable, ToXContent {
+public class DetailAnalyzeResponse implements Streamable, ToXContentFragment {
 
     DetailAnalyzeResponse() {
     }
@@ -190,7 +191,7 @@ public class DetailAnalyzeResponse implements Streamable, ToXContent {
         }
     }
 
-    public static class AnalyzeTokenList implements Streamable, ToXContent {
+    public static class AnalyzeTokenList implements Streamable, ToXContentObject {
         private String name;
         private AnalyzeResponse.AnalyzeToken[] tokens;
 
@@ -216,7 +217,7 @@ public class DetailAnalyzeResponse implements Streamable, ToXContent {
             return list;
         }
 
-        public XContentBuilder toXContentWithoutObject(XContentBuilder builder, Params params) throws IOException {
+        XContentBuilder toXContentWithoutObject(XContentBuilder builder, Params params) throws IOException {
             builder.field(Fields.NAME, this.name);
             builder.startArray(AnalyzeResponse.Fields.TOKENS);
             for (AnalyzeResponse.AnalyzeToken token : tokens) {
@@ -229,12 +230,7 @@ public class DetailAnalyzeResponse implements Streamable, ToXContent {
         @Override
         public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
             builder.startObject();
-            builder.field(Fields.NAME, this.name);
+            toXContentWithoutObject(builder, params);
-            builder.startArray(AnalyzeResponse.Fields.TOKENS);
-            for (AnalyzeResponse.AnalyzeToken token : tokens) {
-                token.toXContent(builder, params);
-            }
-            builder.endArray();
             builder.endObject();
             return builder;
         }
@@ -265,7 +261,7 @@ public class DetailAnalyzeResponse implements Streamable, ToXContent {
         }
     }
 
-    public static class CharFilteredText implements Streamable, ToXContent {
+    public static class CharFilteredText implements Streamable, ToXContentObject {
         private String name;
         private String[] texts;
         CharFilteredText() {

core/src/main/java/org/elasticsearch/action/admin/indices/mapping/get/GetFieldMappingsResponse.java

@@ -24,7 +24,7 @@ import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.common.xcontent.XContentType;
@@ -38,7 +38,7 @@ import static java.util.Collections.emptyMap;
 import static java.util.Collections.unmodifiableMap;
 
 /** Response object for {@link GetFieldMappingsRequest} API */
-public class GetFieldMappingsResponse extends ActionResponse implements ToXContent {
+public class GetFieldMappingsResponse extends ActionResponse implements ToXContentFragment {
 
     private Map<String, Map<String, Map<String, FieldMappingMetaData>>> mappings = emptyMap();
 
@@ -92,7 +92,7 @@ public class GetFieldMappingsResponse extends ActionResponse implements ToXConte
         return builder;
     }
 
-    public static class FieldMappingMetaData implements ToXContent {
+    public static class FieldMappingMetaData implements ToXContentFragment {
         public static final FieldMappingMetaData NULL = new FieldMappingMetaData("", BytesArray.EMPTY);
 
         private String fullName;

core/src/main/java/org/elasticsearch/action/admin/indices/segments/IndicesSegmentResponse.java

@@ -29,7 +29,7 @@ import org.elasticsearch.action.support.broadcast.BroadcastResponse;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.engine.Segment;
 
@@ -39,11 +39,11 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
-import java.util.Locale;
 
-public class IndicesSegmentResponse extends BroadcastResponse implements ToXContent {
+public class IndicesSegmentResponse extends BroadcastResponse implements ToXContentFragment {
 
     private ShardSegments[] shards;
 

core/src/main/java/org/elasticsearch/action/admin/indices/shards/IndicesShardStoresResponse.java

@@ -34,6 +34,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -49,7 +50,7 @@ import static org.elasticsearch.action.admin.indices.shards.IndicesShardStoresRe
  * Consists of {@link StoreStatus}s for requested indices grouped by
  * indices and shard ids and a list of encountered node {@link Failure}s
  */
-public class IndicesShardStoresResponse extends ActionResponse implements ToXContent {
+public class IndicesShardStoresResponse extends ActionResponse implements ToXContentFragment {
 
     /**
      * Shard store information from a node

core/src/main/java/org/elasticsearch/action/admin/indices/stats/CommonStats.java

@@ -25,6 +25,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.cache.query.QueryCacheStats;
 import org.elasticsearch.index.cache.request.RequestCacheStats;
@@ -50,7 +51,7 @@ import java.util.Arrays;
 import java.util.Objects;
 import java.util.stream.Stream;
 
-public class CommonStats implements Writeable, ToXContent {
+public class CommonStats implements Writeable, ToXContentFragment {
 
     @Nullable
     public DocsStats docs;

core/src/main/java/org/elasticsearch/action/admin/indices/stats/IndicesStatsResponse.java

@@ -24,7 +24,7 @@ import org.elasticsearch.action.support.broadcast.BroadcastResponse;
 import org.elasticsearch.cluster.routing.ShardRouting;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 
@@ -38,7 +38,7 @@ import java.util.Set;
 
 import static java.util.Collections.unmodifiableMap;
 
-public class IndicesStatsResponse extends BroadcastResponse implements ToXContent {
+public class IndicesStatsResponse extends BroadcastResponse implements ToXContentFragment {
 
     private ShardStats[] shards;
 

core/src/main/java/org/elasticsearch/action/bulk/BulkItemResponse.java

@@ -34,7 +34,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.StatusToXContentObject;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.seqno.SequenceNumbersService;
@@ -160,7 +160,7 @@ public class BulkItemResponse implements Streamable, StatusToXContentObject {
     /**
      * Represents a failure.
      */
-    public static class Failure implements Writeable, ToXContent {
+    public static class Failure implements Writeable, ToXContentFragment {
         static final String INDEX_FIELD = "index";
         static final String TYPE_FIELD = "type";
         static final String ID_FIELD = "id";

core/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilities.java

@@ -22,20 +22,20 @@ package org.elasticsearch.action.fieldcaps;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
-import java.util.Collections;
-import java.util.Arrays;
-import java.util.List;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.Comparator;
+import java.util.List;
 
 /**
  * Describes the capabilities of a field optionally merged across multiple indices.
  */
-public class FieldCapabilities implements Writeable, ToXContent {
+public class FieldCapabilities implements Writeable, ToXContentObject {
     private final String name;
     private final String type;
     private final boolean isSearchable;

core/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesResponse.java

@@ -23,7 +23,7 @@ import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionResponse;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -34,7 +34,7 @@ import java.util.Map;
 /**
  * Response for {@link FieldCapabilitiesRequest} requests.
  */
-public class FieldCapabilitiesResponse extends ActionResponse implements ToXContent {
+public class FieldCapabilitiesResponse extends ActionResponse implements ToXContentFragment {
     private Map<String, Map<String, FieldCapabilities>> responseMap;
     private List<FieldCapabilitiesIndexResponse> indexResponses;
 

core/src/main/java/org/elasticsearch/action/search/SearchResponseSections.java

@@ -20,7 +20,7 @@
 package org.elasticsearch.action.search;
 
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.search.SearchHits;
 import org.elasticsearch.search.aggregations.Aggregations;
@@ -40,7 +40,7 @@ import java.util.Map;
  * to parse aggregations into, which are not serializable. This is the common part that can be
  * shared between core and client.
  */
-public class SearchResponseSections implements ToXContent {
+public class SearchResponseSections implements ToXContentFragment {
 
     protected final SearchHits hits;
     protected final Aggregations aggregations;

core/src/main/java/org/elasticsearch/cluster/ClusterInfo.java

@@ -20,17 +20,16 @@
 package org.elasticsearch.cluster;
 
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+
 import org.elasticsearch.cluster.routing.ShardRouting;
 import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
-import org.elasticsearch.common.xcontent.ToXContent.Params;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
-import java.util.HashMap;
 import java.util.Map;
 /**
  * ClusterInfo is an object representing a map of nodes to {@link DiskUsage}
@@ -38,7 +37,7 @@ import java.util.Map;
  * <code>InternalClusterInfoService.shardIdentifierFromRouting(String)</code>
  * for the key used in the shardSizes map
  */
-public class ClusterInfo implements ToXContent, Writeable {
+public class ClusterInfo implements ToXContentFragment, Writeable {
     private final ImmutableOpenMap<String, DiskUsage> leastAvailableSpaceUsage;
     private final ImmutableOpenMap<String, DiskUsage> mostAvailableSpaceUsage;
     final ImmutableOpenMap<String, Long> shardSizes;
@@ -117,13 +116,13 @@ public class ClusterInfo implements ToXContent, Writeable {
                 builder.startObject(c.key); { // node
                     builder.field("node_name", c.value.getNodeName());
                     builder.startObject("least_available"); {
-                        c.value.toShortXContent(builder, params);
+                        c.value.toShortXContent(builder);
                     }
                     builder.endObject(); // end "least_available"
                     builder.startObject("most_available"); {
                         DiskUsage most = this.mostAvailableSpaceUsage.get(c.key);
                         if (most != null) {
-                            most.toShortXContent(builder, params);
+                            most.toShortXContent(builder);
                         }
                     }
                     builder.endObject(); // end "most_available"

core/src/main/java/org/elasticsearch/cluster/ClusterState.java

@@ -22,6 +22,7 @@ package org.elasticsearch.cluster;
 import com.carrotsearch.hppc.cursors.IntObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+
 import org.elasticsearch.cluster.block.ClusterBlock;
 import org.elasticsearch.cluster.block.ClusterBlocks;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
@@ -50,6 +51,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.discovery.Discovery;
@@ -85,7 +87,7 @@ import java.util.Set;
  * throws the {@link IncompatibleClusterStateVersionException}, which causes the publishing mechanism to send
  * a full version of the cluster state to the node on which this exception was thrown.
  */
-public class ClusterState implements ToXContent, Diffable<ClusterState> {
+public class ClusterState implements ToXContentFragment, Diffable<ClusterState> {
 
     public static final ClusterState EMPTY_STATE = builder(ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY)).build();
 

core/src/main/java/org/elasticsearch/cluster/DiskUsage.java

@@ -24,7 +24,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -33,7 +33,7 @@ import java.util.Objects;
 /**
  * Encapsulation class used to represent the amount of disk used on a node.
  */
-public class DiskUsage implements ToXContent, Writeable {
+public class DiskUsage implements ToXContentFragment, Writeable {
     final String nodeId;
     final String nodeName;
     final String path;
@@ -73,7 +73,7 @@ public class DiskUsage implements ToXContent, Writeable {
         return Math.round(pct * 10.0) / 10.0;
     }
 
-    public XContentBuilder toShortXContent(XContentBuilder builder, Params params) throws IOException {
+    XContentBuilder toShortXContent(XContentBuilder builder) throws IOException {
         builder.field("path", this.path);
         builder.byteSizeField("total_bytes", "total", this.totalBytes);
         builder.byteSizeField("used_bytes", "used", this.getUsedBytes());
@@ -86,7 +86,7 @@ public class DiskUsage implements ToXContent, Writeable {
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.field("node_id", this.nodeId);
         builder.field("node_name", this.nodeName);
-        builder = toShortXContent(builder, params);
+        builder = toShortXContent(builder);
         return builder;
     }
 

core/src/main/java/org/elasticsearch/cluster/block/ClusterBlock.java

@@ -23,7 +23,7 @@ import org.elasticsearch.Version;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.rest.RestStatus;
 
@@ -32,7 +32,7 @@ import java.util.ArrayList;
 import java.util.EnumSet;
 import java.util.Locale;
 
-public class ClusterBlock implements Streamable, ToXContent {
+public class ClusterBlock implements Streamable, ToXContentFragment {
 
     private int id;
 

core/src/main/java/org/elasticsearch/cluster/health/ClusterIndexHealth.java

@@ -25,7 +25,7 @@ import org.elasticsearch.cluster.routing.IndexShardRoutingTable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -34,7 +34,7 @@ import java.util.Iterator;
 import java.util.Locale;
 import java.util.Map;
 
-public final class ClusterIndexHealth implements Iterable<ClusterShardHealth>, Writeable, ToXContent {
+public final class ClusterIndexHealth implements Iterable<ClusterShardHealth>, Writeable, ToXContentFragment {
 
     private final String index;
     private final int numberOfShards;

core/src/main/java/org/elasticsearch/cluster/metadata/IndexMetaData.java

@@ -23,6 +23,7 @@ import com.carrotsearch.hppc.LongArrayList;
 import com.carrotsearch.hppc.cursors.IntObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+
 import org.elasticsearch.Version;
 import org.elasticsearch.action.support.ActiveShardCount;
 import org.elasticsearch.cluster.Diff;
@@ -45,6 +46,7 @@ import org.elasticsearch.common.settings.Setting.Property;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.loader.SettingsLoader;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentHelper;
@@ -75,7 +77,7 @@ import static org.elasticsearch.cluster.node.DiscoveryNodeFilters.OpType.OR;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
 import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
-public class IndexMetaData implements Diffable<IndexMetaData>, ToXContent {
+public class IndexMetaData implements Diffable<IndexMetaData>, ToXContentFragment {
 
     /**
      * This class will be removed in v7.0

core/src/main/java/org/elasticsearch/cluster/metadata/MetaData.java

@@ -22,6 +22,7 @@ package org.elasticsearch.cluster.metadata;
 import com.carrotsearch.hppc.ObjectHashSet;
 import com.carrotsearch.hppc.cursors.ObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
+
 import org.apache.logging.log4j.Logger;
 import org.apache.lucene.util.CollectionUtil;
 import org.elasticsearch.cluster.Diff;
@@ -45,6 +46,7 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.loader.SettingsLoader;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry.UnknownNamedObjectException;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -70,7 +72,7 @@ import java.util.TreeMap;
 import static org.elasticsearch.common.settings.Settings.readSettingsFromStream;
 import static org.elasticsearch.common.settings.Settings.writeSettingsToStream;
 
-public class MetaData implements Iterable<IndexMetaData>, Diffable<MetaData>, ToXContent {
+public class MetaData implements Iterable<IndexMetaData>, Diffable<MetaData>, ToXContentFragment {
 
     private static final Logger logger = Loggers.getLogger(MetaData.class);
 

core/src/main/java/org/elasticsearch/cluster/node/DiscoveryNode.java

@@ -26,7 +26,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.transport.TransportAddress;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.node.Node;
 
@@ -42,7 +42,7 @@ import java.util.function.Predicate;
 /**
  * A discovery node represents a node that is part of the cluster.
  */
-public class DiscoveryNode implements Writeable, ToXContent {
+public class DiscoveryNode implements Writeable, ToXContentFragment {
 
     public static boolean nodeRequiresLocalStorage(Settings settings) {
         boolean localStorageEnable = Node.NODE_LOCAL_STORAGE_SETTING.get(settings);

core/src/main/java/org/elasticsearch/cluster/routing/AllocationId.java

@@ -26,7 +26,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -42,7 +42,7 @@ import java.util.Objects;
  * relocationId. Once relocation is done, the new allocation id is set to the relocationId. This is similar
  * behavior to how ShardRouting#currentNodeId is used.
  */
-public class AllocationId implements ToXContent, Writeable {
+public class AllocationId implements ToXContentObject, Writeable {
     private static final String ID_KEY = "id";
     private static final String RELOCATION_ID_KEY = "relocation_id";
 

core/src/main/java/org/elasticsearch/cluster/routing/allocation/AbstractAllocationDecision.java

@@ -25,7 +25,7 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -38,7 +38,7 @@ import java.util.stream.Collectors;
 /**
  * An abstract class for representing various types of allocation decisions.
  */
-public abstract class AbstractAllocationDecision implements ToXContent, Writeable {
+public abstract class AbstractAllocationDecision implements ToXContentFragment, Writeable {
 
     @Nullable
     protected final DiscoveryNode targetNode;

core/src/main/java/org/elasticsearch/common/document/DocumentField.java

@@ -22,7 +22,7 @@ package org.elasticsearch.common.document;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.get.GetResult;
@@ -44,7 +44,7 @@ import static org.elasticsearch.common.xcontent.XContentParserUtils.parseStoredF
  * @see SearchHit
  * @see GetResult
  */
-public class DocumentField implements Streamable, ToXContent, Iterable<Object> {
+public class DocumentField implements Streamable, ToXContentFragment, Iterable<Object> {
 
     private String name;
     private List<Object> values;

core/src/main/java/org/elasticsearch/common/geo/builders/ShapeBuilder.java

@@ -22,6 +22,7 @@ package org.elasticsearch.common.geo.builders;
 import com.vividsolutions.jts.geom.Coordinate;
 import com.vividsolutions.jts.geom.Geometry;
 import com.vividsolutions.jts.geom.GeometryFactory;
+
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.Assertions;
 import org.elasticsearch.ElasticsearchParseException;
@@ -31,7 +32,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.logging.ESLoggerFactory;
 import org.elasticsearch.common.unit.DistanceUnit.Distance;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -260,7 +261,7 @@ public abstract class ShapeBuilder extends ToXContentToBytes implements NamedWri
      * Can either be a leaf node consisting of a Coordinate, or a parent with
      * children
      */
-    protected static class CoordinateNode implements ToXContent {
+    protected static class CoordinateNode implements ToXContentObject {
 
         protected final Coordinate coordinate;
         protected final List<CoordinateNode> children;

core/src/main/java/org/elasticsearch/common/unit/Fuzziness.java

@@ -22,7 +22,7 @@ import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -35,7 +35,7 @@ import java.util.Objects;
  * parsing and conversion from similarities to edit distances
  * etc.
  */
-public final class Fuzziness implements ToXContent, Writeable {
+public final class Fuzziness implements ToXContentFragment, Writeable {
 
     public static final String X_FIELD_NAME = "fuzziness";
     public static final Fuzziness ZERO = new Fuzziness(0);
@@ -124,15 +124,7 @@ public final class Fuzziness implements ToXContent, Writeable {
 
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-        return toXContent(builder, params, true);
+        builder.field(X_FIELD_NAME, fuzziness);
-    }
-
-    public XContentBuilder toXContent(XContentBuilder builder, Params params, boolean includeFieldName) throws IOException {
-        if (includeFieldName) {
-            builder.field(X_FIELD_NAME, fuzziness);
-        } else {
-            builder.value(fuzziness);
-        }
         return builder;
     }
 

core/src/main/java/org/elasticsearch/common/xcontent/ToXContentFragment.java

@@ -0,0 +1,36 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.common.xcontent;
+
+/**
+ * An interface allowing to transfer an object to "XContent" using an
+ * {@link XContentBuilder}. The difference between {@link ToXContentFragment}
+ * and {@link ToXContentObject} is that the former outputs a fragment that
+ * requires to start and end a new anonymous object externally, while the latter
+ * guarantees that what gets printed out is fully valid syntax without any
+ * external addition.
+ */
+public interface ToXContentFragment extends ToXContent {
+
+    @Override
+    default boolean isFragment() {
+        return true;
+    }
+}

core/src/main/java/org/elasticsearch/common/xcontent/ToXContentObject.java

@@ -20,10 +20,12 @@
 package org.elasticsearch.common.xcontent;
 
 /**
- * An interface allowing to transfer an object to "XContent" using an {@link XContentBuilder}.
+ * An interface allowing to transfer an object to "XContent" using an
- * The difference between {@link ToXContent} and {@link ToXContentObject} is that the former may output a fragment that
+ * {@link XContentBuilder}. The difference between {@link ToXContentFragment}
- * requires to start and end a new anonymous object externally, while the latter guarantees that what gets printed
+ * and {@link ToXContentObject} is that the former outputs a fragment that
- * out is fully valid syntax without any external addition.
+ * requires to start and end a new anonymous object externally, while the latter
+ * guarantees that what gets printed out is fully valid syntax without any
+ * external addition.
  */
 public interface ToXContentObject extends ToXContent {
 

core/src/main/java/org/elasticsearch/discovery/DiscoveryStats.java

@@ -23,13 +23,13 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.discovery.zen.PendingClusterStateStats;
 
 import java.io.IOException;
 
-public class DiscoveryStats implements Writeable, ToXContent {
+public class DiscoveryStats implements Writeable, ToXContentFragment {
 
     @Nullable
     private final PendingClusterStateStats queueStats;

core/src/main/java/org/elasticsearch/http/HttpInfo.java

@@ -24,12 +24,12 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.transport.BoundTransportAddress;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class HttpInfo implements Writeable, ToXContent {
+public class HttpInfo implements Writeable, ToXContentFragment {
 
     private final BoundTransportAddress address;
     private final long maxContentLength;

core/src/main/java/org/elasticsearch/http/HttpStats.java

@@ -22,12 +22,12 @@ package org.elasticsearch.http;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class HttpStats implements Writeable, ToXContent {
+public class HttpStats implements Writeable, ToXContentFragment {
 
     private final long serverOpen;
     private final long totalOpen;

core/src/main/java/org/elasticsearch/index/Index.java

@@ -25,7 +25,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -35,7 +35,7 @@ import java.util.Objects;
 /**
  * A value class representing the basic required properties of an Elasticsearch index.
  */
-public class Index implements Writeable, ToXContent {
+public class Index implements Writeable, ToXContentObject {
 
     public static final Index[] EMPTY_ARRAY = new Index[0];
     private static final String INDEX_UUID_KEY = "index_uuid";

core/src/main/java/org/elasticsearch/index/engine/CommitStats.java

@@ -24,7 +24,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.lucene.Lucene;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -32,7 +32,7 @@ import java.util.Base64;
 import java.util.Map;
 
 /** a class the returns dynamic information with respect to the last commit point of this shard */
-public final class CommitStats implements Streamable, ToXContent {
+public final class CommitStats implements Streamable, ToXContentFragment {
 
     private Map<String, String> userData;
     private long generation;

core/src/main/java/org/elasticsearch/index/fielddata/FieldDataStats.java

@@ -25,13 +25,13 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 import java.util.Objects;
 
-public class FieldDataStats implements Streamable, ToXContent {
+public class FieldDataStats implements Streamable, ToXContentFragment {
 
     private static final String FIELDDATA = "fielddata";
     private static final String MEMORY_SIZE = "memory_size";

core/src/main/java/org/elasticsearch/index/flush/FlushStats.java

@@ -23,12 +23,12 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class FlushStats implements Streamable, ToXContent {
+public class FlushStats implements Streamable, ToXContentFragment {
 
     private long total;
 

core/src/main/java/org/elasticsearch/index/get/GetStats.java

@@ -23,12 +23,12 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class GetStats implements Streamable, ToXContent {
+public class GetStats implements Streamable, ToXContentFragment {
 
     private long existsCount;
     private long existsTimeInMillis;

core/src/main/java/org/elasticsearch/index/mapper/DocumentMapper.java

@@ -28,6 +28,7 @@ import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.text.Text;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.index.IndexSettings;
@@ -47,7 +48,7 @@ import java.util.Objects;
 
 import static java.util.Collections.emptyMap;
 
-public class DocumentMapper implements ToXContent {
+public class DocumentMapper implements ToXContentFragment {
 
     public static class Builder {
 

core/src/main/java/org/elasticsearch/index/mapper/DynamicTemplate.java

@@ -23,7 +23,7 @@ import org.elasticsearch.Version;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.regex.Regex;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -34,7 +34,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
 
-public class DynamicTemplate implements ToXContent {
+public class DynamicTemplate implements ToXContentObject {
 
     private static final DeprecationLogger DEPRECATION_LOGGER = new DeprecationLogger(Loggers.getLogger(DynamicTemplate.class));
 

core/src/main/java/org/elasticsearch/index/mapper/Mapper.java

@@ -21,7 +21,7 @@ package org.elasticsearch.index.mapper;
 
 import org.elasticsearch.Version;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.index.analysis.IndexAnalyzers;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.index.similarity.SimilarityProvider;
@@ -31,7 +31,7 @@ import java.util.Objects;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
-public abstract class Mapper implements ToXContent, Iterable<Mapper> {
+public abstract class Mapper implements ToXContentFragment, Iterable<Mapper> {
 
     public static class BuilderContext {
         private final Settings indexSettings;

core/src/main/java/org/elasticsearch/index/mapper/Mapping.java

@@ -21,6 +21,7 @@ package org.elasticsearch.index.mapper;
 
 import org.elasticsearch.Version;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 
@@ -38,7 +39,7 @@ import static java.util.Collections.unmodifiableMap;
  * Wrapper around everything that defines a mapping, without references to
  * utility classes like MapperService, ...
  */
-public final class Mapping implements ToXContent {
+public final class Mapping implements ToXContentFragment {
 
     final Version indexCreated;
     final RootObjectMapper root;

core/src/main/java/org/elasticsearch/index/merge/MergeStats.java

@@ -24,12 +24,12 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class MergeStats implements Streamable, ToXContent {
+public class MergeStats implements Streamable, ToXContentFragment {
 
     private long total;
     private long totalTimeInMillis;

core/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java

@@ -45,7 +45,7 @@ import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.lucene.search.MoreLikeThisQuery;
 import org.elasticsearch.common.lucene.search.XMoreLikeThis;
 import org.elasticsearch.common.lucene.uid.Versions;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -142,7 +142,7 @@ public class MoreLikeThisQueryBuilder extends AbstractQueryBuilder<MoreLikeThisQ
     /**
      * A single item to be used for a {@link MoreLikeThisQueryBuilder}.
      */
-    public static final class Item implements ToXContent, Writeable {
+    public static final class Item implements ToXContentObject, Writeable {
         public static final Item[] EMPTY_ARRAY = new Item[0];
 
         public interface Field {

core/src/main/java/org/elasticsearch/index/query/functionscore/FunctionScoreQueryBuilder.java

@@ -29,7 +29,7 @@ import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.lucene.search.function.CombineFunction;
 import org.elasticsearch.common.lucene.search.function.FunctionScoreQuery;
 import org.elasticsearch.common.lucene.search.function.ScoreFunction;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentLocation;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -328,7 +328,7 @@ public class FunctionScoreQueryBuilder extends AbstractQueryBuilder<FunctionScor
      * Function to be associated with an optional filter, meaning it will be executed only for the documents
      * that match the given filter.
      */
-    public static class FilterFunctionBuilder implements ToXContent, Writeable {
+    public static class FilterFunctionBuilder implements ToXContentObject, Writeable {
         private final QueryBuilder filter;
         private final ScoreFunctionBuilder<?> scoreFunction;
 

core/src/main/java/org/elasticsearch/index/reindex/BulkByScrollResponse.java

@@ -25,7 +25,7 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -40,7 +40,7 @@ import static org.elasticsearch.common.unit.TimeValue.timeValueNanos;
 /**
  * Response used for actions that index many documents using a scroll request.
  */
-public class BulkByScrollResponse extends ActionResponse implements ToXContent {
+public class BulkByScrollResponse extends ActionResponse implements ToXContentFragment {
     private TimeValue took;
     private BulkByScrollTask.Status status;
     private List<Failure> bulkFailures;

core/src/main/java/org/elasticsearch/index/shard/DocsStats.java

@@ -22,12 +22,12 @@ package org.elasticsearch.index.shard;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class DocsStats implements Streamable, ToXContent {
+public class DocsStats implements Streamable, ToXContentFragment {
 
     long count = 0;
     long deleted = 0;

core/src/main/java/org/elasticsearch/index/shard/IndexingStats.java

@@ -19,20 +19,20 @@
 
 package org.elasticsearch.index.shard;
 
-import org.elasticsearch.Version;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 
-public class IndexingStats implements Streamable, ToXContent {
+public class IndexingStats implements Streamable, ToXContentFragment {
 
     public static class Stats implements Streamable, ToXContent {
 

core/src/main/java/org/elasticsearch/index/snapshots/blobstore/BlobStoreIndexShardSnapshot.java

@@ -27,6 +27,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.store.StoreFileMetaData;
@@ -39,7 +40,7 @@ import java.util.List;
 /**
  * Shard snapshot metadata
  */
-public class BlobStoreIndexShardSnapshot implements ToXContent {
+public class BlobStoreIndexShardSnapshot implements ToXContentFragment {
 
     /**
      * Information about snapshotted file

core/src/main/java/org/elasticsearch/index/snapshots/blobstore/BlobStoreIndexShardSnapshots.java

@@ -21,7 +21,7 @@ package org.elasticsearch.index.snapshots.blobstore;
 
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.ParseField;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.snapshots.blobstore.BlobStoreIndexShardSnapshot.FileInfo;
@@ -42,7 +42,7 @@ import static java.util.Collections.unmodifiableMap;
  * This class is used to find files that were already snapshotted and clear out files that no longer referenced by any
  * snapshots
  */
-public class BlobStoreIndexShardSnapshots implements Iterable<SnapshotFiles>, ToXContent {
+public class BlobStoreIndexShardSnapshots implements Iterable<SnapshotFiles>, ToXContentFragment {
 
     private final List<SnapshotFiles> shardSnapshots;
     private final Map<String, FileInfo> files;

core/src/main/java/org/elasticsearch/indices/breaker/AllCircuitBreakerStats.java

@@ -22,7 +22,7 @@ package org.elasticsearch.indices.breaker;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -30,7 +30,7 @@ import java.io.IOException;
 /**
  * Stats class encapsulating all of the different circuit breaker stats
  */
-public class AllCircuitBreakerStats implements Writeable, ToXContent {
+public class AllCircuitBreakerStats implements Writeable, ToXContentFragment {
 
     private final CircuitBreakerStats[] allStats;
 

core/src/main/java/org/elasticsearch/indices/breaker/CircuitBreakerStats.java

@@ -23,7 +23,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -32,7 +32,7 @@ import java.util.Locale;
 /**
  * Class encapsulating stats about the circuit breaker
  */
-public class CircuitBreakerStats implements Writeable, ToXContent {
+public class CircuitBreakerStats implements Writeable, ToXContentObject {
 
     private final String name;
     private final long limit;

core/src/main/java/org/elasticsearch/indices/recovery/RecoveryState.java

@@ -28,6 +28,8 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.index.shard.ShardId;
@@ -552,7 +554,7 @@ public class RecoveryState implements ToXContent, Streamable {
         }
     }
 
-    public static class File implements ToXContent, Streamable {
+    public static class File implements ToXContentObject, Streamable {
         private String name;
         private long length;
         private long recovered;
@@ -663,7 +665,7 @@ public class RecoveryState implements ToXContent, Streamable {
         }
     }
 
-    public static class Index extends Timer implements ToXContent, Streamable {
+    public static class Index extends Timer implements ToXContentFragment, Streamable {
 
         private Map<String, File> fileDetails = new HashMap<>();
 

core/src/main/java/org/elasticsearch/ingest/IngestInfo.java

@@ -22,7 +22,7 @@ package org.elasticsearch.ingest;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -31,7 +31,7 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.TreeSet;
 
-public class IngestInfo implements Writeable, ToXContent {
+public class IngestInfo implements Writeable, ToXContentFragment {
 
     private final Set<ProcessorInfo> processors;
 

core/src/main/java/org/elasticsearch/ingest/IngestStats.java

@@ -23,6 +23,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -30,7 +31,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
-public class IngestStats implements Writeable, ToXContent {
+public class IngestStats implements Writeable, ToXContentFragment {
     private final Stats totalStats;
     private final Map<String, Stats> statsPerPipeline;
 

core/src/main/java/org/elasticsearch/monitor/fs/FsInfo.java

@@ -27,6 +27,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -35,7 +36,7 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
 
-public class FsInfo implements Iterable<FsInfo.Path>, Writeable, ToXContent {
+public class FsInfo implements Iterable<FsInfo.Path>, Writeable, ToXContentFragment {
 
     public static class Path implements Writeable, ToXContent {
 
@@ -178,7 +179,7 @@ public class FsInfo implements Iterable<FsInfo.Path>, Writeable, ToXContent {
         }
     }
 
-    public static class DeviceStats implements Writeable, ToXContent {
+    public static class DeviceStats implements Writeable, ToXContentFragment {
 
         final int majorDeviceNumber;
         final int minorDeviceNumber;
@@ -313,7 +314,7 @@ public class FsInfo implements Iterable<FsInfo.Path>, Writeable, ToXContent {
 
     }
 
-    public static class IoStats implements Writeable, ToXContent {
+    public static class IoStats implements Writeable, ToXContentFragment {
 
         private static final String OPERATIONS = "operations";
         private static final String READ_OPERATIONS = "read_operations";

core/src/main/java/org/elasticsearch/monitor/jvm/JvmInfo.java

@@ -23,7 +23,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -39,7 +39,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
-public class JvmInfo implements Writeable, ToXContent {
+public class JvmInfo implements Writeable, ToXContentFragment {
 
     private static JvmInfo INSTANCE;
 

core/src/main/java/org/elasticsearch/monitor/jvm/JvmStats.java

@@ -24,7 +24,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -44,7 +44,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
-public class JvmStats implements Writeable, ToXContent {
+public class JvmStats implements Writeable, ToXContentFragment {
 
     private static final RuntimeMXBean runtimeMXBean;
     private static final MemoryMXBean memoryMXBean;

core/src/main/java/org/elasticsearch/monitor/os/OsStats.java

@@ -25,6 +25,8 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
@@ -125,7 +127,7 @@ public class OsStats implements Writeable, ToXContent {
         return builder;
     }
 
-    public static class Cpu implements Writeable, ToXContent {
+    public static class Cpu implements Writeable, ToXContentFragment {
 
         private final short percent;
         private final double[] loadAverage;
@@ -229,7 +231,7 @@ public class OsStats implements Writeable, ToXContent {
         }
     }
 
-    public static class Mem implements Writeable, ToXContent {
+    public static class Mem implements Writeable, ToXContentFragment {
 
         private final long total;
         private final long free;
@@ -286,7 +288,7 @@ public class OsStats implements Writeable, ToXContent {
     /**
      * Encapsulates basic cgroup statistics.
      */
-    public static class Cgroup implements Writeable, ToXContent {
+    public static class Cgroup implements Writeable, ToXContentObject {
 
         private final String cpuAcctControlGroup;
         private final long cpuAcctUsageNanos;
@@ -415,7 +417,7 @@ public class OsStats implements Writeable, ToXContent {
         /**
          * Encapsulates CPU time statistics.
          */
-        public static class CpuStat implements Writeable, ToXContent {
+        public static class CpuStat implements Writeable, ToXContentFragment {
 
             private final long numberOfElapsedPeriods;
             private final long numberOfTimesThrottled;

core/src/main/java/org/elasticsearch/repositories/IndexId.java

@@ -23,6 +23,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.Index;
 
@@ -32,7 +33,7 @@ import java.util.Objects;
 /**
  * Represents a single snapshotted index in the repository.
  */
-public final class IndexId implements Writeable, ToXContent {
+public final class IndexId implements Writeable, ToXContentObject {
     protected static final String NAME = "name";
     protected static final String ID = "id";
 

core/src/main/java/org/elasticsearch/search/aggregations/AggregationBuilder.java

@@ -19,10 +19,10 @@
 package org.elasticsearch.search.aggregations;
 
 
-import org.elasticsearch.action.support.ToXContentToBytes;
 import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.NamedWriteable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.query.QueryRewriteContext;
 import org.elasticsearch.search.internal.SearchContext;
@@ -35,8 +35,7 @@ import java.util.Map;
  * A factory that knows how to create an {@link Aggregator} of a specific type.
  */
 public abstract class AggregationBuilder
-    extends ToXContentToBytes
+        implements NamedWriteable, ToXContentFragment, BaseAggregationBuilder {
-    implements NamedWriteable, ToXContent, BaseAggregationBuilder {
 
     protected final String name;
     protected AggregatorFactories.Builder factoriesBuilder = AggregatorFactories.builder();
@@ -139,4 +138,9 @@ public abstract class AggregationBuilder
     public static final class CommonFields extends ParseField.CommonFields {
         public static final ParseField VALUE_TYPE = new ParseField("value_type");
     }
+
+    @Override
+    public String toString() {
+        return Strings.toString(this);
+    }
 }

core/src/main/java/org/elasticsearch/search/aggregations/Aggregations.java

@@ -20,7 +20,7 @@ package org.elasticsearch.search.aggregations;
 
 import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.common.ParsingException;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -40,7 +40,7 @@ import static org.elasticsearch.common.xcontent.XContentParserUtils.parseTypedKe
 /**
  * Represents a set of {@link Aggregation}s
  */
-public class Aggregations implements Iterable<Aggregation>, ToXContent {
+public class Aggregations implements Iterable<Aggregation>, ToXContentFragment {
 
     public static final String AGGREGATIONS_FIELD = "aggregations";
 

core/src/main/java/org/elasticsearch/search/aggregations/InternalAggregation.java

@@ -23,7 +23,6 @@ import org.elasticsearch.common.io.stream.NamedWriteable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.util.BigArrays;
-import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.rest.action.search.RestSearchAction;
 import org.elasticsearch.script.ScriptService;
@@ -38,7 +37,7 @@ import java.util.Objects;
 /**
  * An internal implementation of {@link Aggregation}. Serves as a base class for all aggregation implementations.
  */
-public abstract class InternalAggregation implements Aggregation, ToXContent, NamedWriteable {
+public abstract class InternalAggregation implements Aggregation, NamedWriteable {
 
     public static class ReduceContext {
 

core/src/main/java/org/elasticsearch/search/aggregations/InternalAggregations.java

@@ -21,7 +21,6 @@ package org.elasticsearch.search.aggregations;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
-import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.search.aggregations.InternalAggregation.ReduceContext;
 
 import java.io.IOException;
@@ -35,7 +34,7 @@ import static java.util.Collections.emptyMap;
 /**
  * An internal implementation of {@link Aggregations}.
  */
-public final class InternalAggregations extends Aggregations implements ToXContent, Streamable {
+public final class InternalAggregations extends Aggregations implements Streamable {
 
     public static final InternalAggregations EMPTY = new InternalAggregations();
 

core/src/main/java/org/elasticsearch/search/aggregations/bucket/adjacency/AdjacencyMatrixAggregator.java

@@ -28,7 +28,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.xcontent.ObjectParser.NamedObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.query.QueryBuilder;
@@ -63,7 +63,7 @@ public class AdjacencyMatrixAggregator extends BucketsAggregator {
 
     public static final ParseField FILTERS_FIELD = new ParseField("filters");
 
-    protected static class KeyedFilter implements Writeable, ToXContent {
+    protected static class KeyedFilter implements Writeable, ToXContentFragment {
         private final String key;
         private final QueryBuilder filter;
 

core/src/main/java/org/elasticsearch/search/aggregations/bucket/filter/FiltersAggregator.java

@@ -27,7 +27,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.lucene.Lucene;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.search.aggregations.Aggregator;
@@ -52,7 +52,7 @@ public class FiltersAggregator extends BucketsAggregator {
     public static final ParseField OTHER_BUCKET_FIELD = new ParseField("other_bucket");
     public static final ParseField OTHER_BUCKET_KEY_FIELD = new ParseField("other_bucket_key");
 
-    public static class KeyedFilter implements Writeable, ToXContent {
+    public static class KeyedFilter implements Writeable, ToXContentFragment {
         private final String key;
         private final QueryBuilder filter;
 

core/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/ExtendedBounds.java

@@ -27,7 +27,7 @@ import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.rounding.Rounding;
 import org.elasticsearch.common.xcontent.ConstructingObjectParser;
 import org.elasticsearch.common.xcontent.ObjectParser.ValueType;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentParser.Token;
@@ -40,7 +40,7 @@ import java.util.Objects;
 
 import static org.elasticsearch.common.xcontent.ConstructingObjectParser.optionalConstructorArg;
 
-public class ExtendedBounds implements ToXContent, Writeable {
+public class ExtendedBounds implements ToXContentFragment, Writeable {
     static final ParseField EXTENDED_BOUNDS_FIELD = Histogram.EXTENDED_BOUNDS_FIELD;
     static final ParseField MIN_FIELD = new ParseField("min");
     static final ParseField MAX_FIELD = new ParseField("max");

core/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/InternalSignificantTerms.java

@@ -20,7 +20,6 @@ package org.elasticsearch.search.aggregations.bucket.significant;
 
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.Aggregations;
@@ -42,7 +41,7 @@ import java.util.Objects;
  * Result of the significant terms aggregation.
  */
 public abstract class InternalSignificantTerms<A extends InternalSignificantTerms<A, B>, B extends InternalSignificantTerms.Bucket<B>>
-        extends InternalMultiBucketAggregation<A, B> implements SignificantTerms, ToXContent {
+        extends InternalMultiBucketAggregation<A, B> implements SignificantTerms {
 
     public static final String SCORE = "score";
     public static final String BG_COUNT = "bg_count";

core/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/IncludeExclude.java

@@ -41,7 +41,7 @@ import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.search.DocValueFormat;
@@ -57,7 +57,7 @@ import java.util.TreeSet;
  * Defines the include/exclude regular expression filtering for string terms aggregation. In this filtering logic,
  * exclusion has precedence, where the {@code include} is evaluated first and then the {@code exclude}.
  */
-public class IncludeExclude implements Writeable, ToXContent {
+public class IncludeExclude implements Writeable, ToXContentFragment {
     public static final ParseField INCLUDE_FIELD = new ParseField("include");
     public static final ParseField EXCLUDE_FIELD = new ParseField("exclude");
     public static final ParseField PARTITION_FIELD = new ParseField("partition");

core/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/InternalTerms.java

@@ -21,18 +21,17 @@ package org.elasticsearch.search.aggregations.bucket.terms;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.AggregationExecutionException;
 import org.elasticsearch.search.aggregations.Aggregations;
+import org.elasticsearch.search.aggregations.BucketOrder;
 import org.elasticsearch.search.aggregations.InternalAggregation;
 import org.elasticsearch.search.aggregations.InternalAggregations;
 import org.elasticsearch.search.aggregations.InternalMultiBucketAggregation;
-import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
-import org.elasticsearch.search.aggregations.BucketOrder;
 import org.elasticsearch.search.aggregations.InternalOrder;
 import org.elasticsearch.search.aggregations.KeyComparable;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -43,7 +42,7 @@ import java.util.Map;
 import java.util.Objects;
 
 public abstract class InternalTerms<A extends InternalTerms<A, B>, B extends InternalTerms.Bucket<B>>
-        extends InternalMultiBucketAggregation<A, B> implements Terms, ToXContent {
+        extends InternalMultiBucketAggregation<A, B> implements Terms {
 
     protected static final ParseField DOC_COUNT_ERROR_UPPER_BOUND_FIELD_NAME = new ParseField("doc_count_error_upper_bound");
     protected static final ParseField SUM_OF_OTHER_DOC_COUNTS = new ParseField("sum_other_doc_count");

core/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregator.java

@@ -25,21 +25,21 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.util.Comparators;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.Aggregator;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
+import org.elasticsearch.search.aggregations.BucketOrder;
+import org.elasticsearch.search.aggregations.InternalOrder;
+import org.elasticsearch.search.aggregations.InternalOrder.Aggregation;
+import org.elasticsearch.search.aggregations.InternalOrder.CompoundOrder;
 import org.elasticsearch.search.aggregations.bucket.BucketsAggregator;
 import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation.Bucket;
 import org.elasticsearch.search.aggregations.bucket.SingleBucketAggregator;
 import org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 import org.elasticsearch.search.aggregations.support.AggregationPath;
-import org.elasticsearch.search.aggregations.BucketOrder;
-import org.elasticsearch.search.aggregations.InternalOrder;
-import org.elasticsearch.search.aggregations.InternalOrder.Aggregation;
-import org.elasticsearch.search.aggregations.InternalOrder.CompoundOrder;
 import org.elasticsearch.search.internal.SearchContext;
 
 import java.io.IOException;
@@ -52,7 +52,7 @@ import java.util.Set;
 
 public abstract class TermsAggregator extends BucketsAggregator {
 
-    public static class BucketCountThresholds implements Writeable, ToXContent {
+    public static class BucketCountThresholds implements Writeable, ToXContentFragment {
         private long minDocCount;
         private long shardMinDocCount;
         private int requiredSize;

core/src/main/java/org/elasticsearch/search/aggregations/pipeline/movavg/models/MovAvgModel.java

@@ -22,7 +22,7 @@ package org.elasticsearch.search.aggregations.pipeline.movavg.models;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.io.stream.NamedWriteable;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 
 import java.io.IOException;
 import java.text.ParseException;
@@ -30,7 +30,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Map;
 
-public abstract class MovAvgModel implements NamedWriteable, ToXContent {
+public abstract class MovAvgModel implements NamedWriteable, ToXContentFragment {
 
     /**
      * Should this model be fit to the data via a cost minimizing algorithm by default?

core/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -1245,7 +1245,7 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
         return builder;
     }
 
-    public static class IndexBoost implements Writeable, ToXContent {
+    public static class IndexBoost implements Writeable, ToXContentObject {
         private final String index;
         private final float boost;
 

core/src/main/java/org/elasticsearch/search/fetch/subphase/FetchSourceContext.java

@@ -26,7 +26,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.support.XContentMapValues;
@@ -42,7 +42,7 @@ import java.util.function.Function;
 /**
  * Context used to fetch the {@code _source}.
  */
-public class FetchSourceContext implements Writeable, ToXContent {
+public class FetchSourceContext implements Writeable, ToXContentObject {
 
     public static final ParseField INCLUDES_FIELD = new ParseField("includes", "include");
     public static final ParseField EXCLUDES_FIELD = new ParseField("excludes", "exclude");

core/src/main/java/org/elasticsearch/search/fetch/subphase/highlight/HighlightField.java

@@ -24,7 +24,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.text.Text;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -39,7 +39,7 @@ import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureExpect
 /**
  * A field highlighted with its highlighted fragments.
  */
-public class HighlightField implements ToXContent, Streamable {
+public class HighlightField implements ToXContentFragment, Streamable {
 
     private String name;
 

core/src/main/java/org/elasticsearch/search/internal/InternalSearchResponse.java

@@ -23,7 +23,7 @@ import org.elasticsearch.action.search.SearchResponseSections;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.search.SearchHits;
 import org.elasticsearch.search.aggregations.InternalAggregations;
 import org.elasticsearch.search.profile.SearchProfileShardResults;
@@ -34,7 +34,7 @@ import java.io.IOException;
 /**
  * {@link SearchResponseSections} subclass that can be serialized over the wire.
  */
-public class InternalSearchResponse extends SearchResponseSections implements Writeable, ToXContent {
+public class InternalSearchResponse extends SearchResponseSections implements Writeable, ToXContentFragment {
 
     public static InternalSearchResponse empty() {
         return new InternalSearchResponse(SearchHits.empty(), null, null, null, false, null, 1);

core/src/main/java/org/elasticsearch/search/profile/aggregation/AggregationProfileShardResult.java

@@ -22,7 +22,7 @@ package org.elasticsearch.search.profile.aggregation;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.search.profile.ProfileResult;
@@ -38,7 +38,7 @@ import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureExpect
  * A container class to hold the profile results for a single shard in the request.
  * Contains a list of query profiles, a collector tree and a total rewrite tree.
  */
-public final class AggregationProfileShardResult implements Writeable, ToXContent {
+public final class AggregationProfileShardResult implements Writeable, ToXContentFragment {
 
     public static final String AGGREGATIONS = "aggregations";
     private final List<ProfileResult> aggProfileResults;

core/src/main/java/org/elasticsearch/search/suggest/completion/CompletionStats.java

@@ -24,12 +24,12 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Streamable;
 import org.elasticsearch.common.unit.ByteSizeValue;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
 
-public class CompletionStats implements Streamable, ToXContent {
+public class CompletionStats implements Streamable, ToXContentFragment {
 
     private static final String COMPLETION = "completion";
     private static final String SIZE_IN_BYTES = "size_in_bytes";

core/src/main/java/org/elasticsearch/search/suggest/completion/FuzzyOptions.java

@@ -27,7 +27,7 @@ import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.Fuzziness;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -37,7 +37,7 @@ import java.util.Objects;
 /**
  * Fuzzy options for completion suggester
  */
-public class FuzzyOptions implements ToXContent, Writeable {
+public class FuzzyOptions implements ToXContentFragment, Writeable {
     static final ParseField FUZZY_OPTIONS = new ParseField("fuzzy");
     private static final ParseField TRANSPOSITION_FIELD = new ParseField("transpositions");
     private static final ParseField MIN_LENGTH_FIELD = new ParseField("min_length");

core/src/main/java/org/elasticsearch/search/suggest/completion/context/CategoryQueryContext.java

@@ -23,7 +23,7 @@ import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -37,7 +37,7 @@ import static org.elasticsearch.search.suggest.completion.context.CategoryContex
 /**
  * Defines the query context for {@link CategoryContextMapping}
  */
-public final class CategoryQueryContext implements ToXContent {
+public final class CategoryQueryContext implements ToXContentObject {
     public static final String NAME = "category";
 
     private final String category;

core/src/main/java/org/elasticsearch/search/suggest/completion/context/ContextMapping.java

@@ -21,6 +21,7 @@ package org.elasticsearch.search.suggest.completion.context;
 
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentParser.Token;
@@ -40,7 +41,7 @@ import java.util.Set;
  *
  * Implementations have to define how contexts are parsed at query/index time
  */
-public abstract class ContextMapping<T extends ToXContent> implements ToXContent {
+public abstract class ContextMapping<T extends ToXContent> implements ToXContentFragment {
 
     public static final String FIELD_TYPE = "type";
     public static final String FIELD_NAME = "name";

core/src/main/java/org/elasticsearch/search/suggest/completion/context/ContextMappings.java

@@ -30,6 +30,7 @@ import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.mapper.CompletionFieldMapper;
 import org.elasticsearch.index.mapper.DocumentMapperParser;
 import org.elasticsearch.index.mapper.ParseContext;
+import org.elasticsearch.search.suggest.completion.context.ContextMapping.Type;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -43,7 +44,6 @@ import java.util.Set;
 
 import static org.elasticsearch.search.suggest.completion.context.ContextMapping.FIELD_NAME;
 import static org.elasticsearch.search.suggest.completion.context.ContextMapping.FIELD_TYPE;
-import static org.elasticsearch.search.suggest.completion.context.ContextMapping.Type;
 
 /**
  * ContextMappings indexes context-enabled suggestion fields

core/src/main/java/org/elasticsearch/search/suggest/completion/context/GeoQueryContext.java

@@ -24,7 +24,7 @@ import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.geo.GeoPoint;
 import org.elasticsearch.common.geo.GeoUtils;
 import org.elasticsearch.common.xcontent.ObjectParser;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 
@@ -41,7 +41,7 @@ import static org.elasticsearch.search.suggest.completion.context.GeoContextMapp
 /**
  * Defines the query context for {@link GeoContextMapping}
  */
-public final class GeoQueryContext implements ToXContent {
+public final class GeoQueryContext implements ToXContentObject {
     public static final String NAME = "geo";
 
     private final GeoPoint geoPoint;

core/src/main/java/org/elasticsearch/threadpool/ThreadPool.java

@@ -40,7 +40,7 @@ import org.elasticsearch.common.util.concurrent.EsRejectedExecutionException;
 import org.elasticsearch.common.util.concurrent.EsThreadPoolExecutor;
 import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.common.util.concurrent.XRejectedExecutionHandler;
-import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.node.Node;
 
@@ -582,7 +582,7 @@ public class ThreadPool extends AbstractComponent implements Closeable {
         }
     }
 
-    public static class Info implements Writeable, ToXContent {
+    public static class Info implements Writeable, ToXContentFragment {
 
         private final String name;
         private final ThreadPoolType type;

core/src/test/java/org/elasticsearch/common/xcontent/ConstructingObjectParserTests.java

@@ -315,7 +315,7 @@ public class ConstructingObjectParserTests extends ESTestCase {
         assertEquals(-8, parsed.mineral);
     }
 
-    private static class HasCtorArguments implements ToXContent {
+    private static class HasCtorArguments implements ToXContentObject {
         @Nullable
         final String animal;
         @Nullable

core/src/test/java/org/elasticsearch/gateway/MetaDataStateFormatTests.java

@@ -37,6 +37,7 @@ import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -368,7 +369,7 @@ public class MetaDataStateFormatTests extends ESTestCase {
         }
     }
 
-    private static class DummyState implements ToXContent {
+    private static class DummyState implements ToXContentFragment {
         String string;
         int aInt;
         long aLong;

core/src/test/java/org/elasticsearch/snapshots/BlobStoreFormatIT.java

@@ -32,6 +32,7 @@ import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentType;
@@ -56,7 +57,7 @@ public class BlobStoreFormatIT extends AbstractSnapshotIntegTestCase {
 
     public static final String BLOB_CODEC = "blob";
 
-    private static class BlobObj implements ToXContent {
+    private static class BlobObj implements ToXContentFragment {
 
         private final String text;
 

test/framework/src/main/java/org/elasticsearch/search/aggregations/BaseAggregationTestCase.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.search.aggregations;
 
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.NamedWriteableAwareStreamInput;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
@@ -124,6 +125,20 @@ public abstract class BaseAggregationTestCase<AB extends AbstractAggregationBuil
         assertEquals(testAgg.hashCode(), newAgg.hashCode());
     }
 
+    /**
+     * Generic test that checks that the toString method renders the XContent
+     * correctly.
+     */
+    public void testToString() throws IOException {
+        AB testAgg = createTestAggregatorBuilder();
+        String toString = randomBoolean() ? Strings.toString(testAgg) : testAgg.toString();
+        XContentParser parser = createParser(XContentType.JSON.xContent(), toString);
+        AggregationBuilder newAgg = parse(parser);
+        assertNotSame(newAgg, testAgg);
+        assertEquals(testAgg, newAgg);
+        assertEquals(testAgg.hashCode(), newAgg.hashCode());
+    }
+
     protected AggregationBuilder parse(XContentParser parser) throws IOException {
         assertSame(XContentParser.Token.START_OBJECT, parser.nextToken());
         AggregatorFactories.Builder parsed = AggregatorFactories.parseAggregators(parser);

test/framework/src/main/java/org/elasticsearch/test/AbstractQueryTestCase.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.test;
 
 import com.fasterxml.jackson.core.io.JsonStringEncoder;
+
 import org.apache.lucene.search.BoostQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.TermQuery;
@@ -740,6 +741,21 @@ public abstract class AbstractQueryTestCase<QB extends AbstractQueryBuilder<QB>>
         }
     }
 
+    /**
+     * Generic test that checks that the <code>Strings.toString()</code> method
+     * renders the XContent correctly.
+     */
+    public void testValidOutput() throws IOException {
+        for (int runs = 0; runs < NUMBER_OF_TESTQUERIES; runs++) {
+            QB testQuery = createTestQueryBuilder();
+            XContentType xContentType = XContentType.JSON;
+            String toString = Strings.toString(testQuery);
+            assertParsedQuery(createParser(xContentType.xContent(), toString), testQuery);
+            BytesReference bytes = XContentHelper.toXContent(testQuery, xContentType, false);
+            assertParsedQuery(createParser(xContentType.xContent(), bytes), testQuery);
+        }
+    }
+
     private QB changeNameOrBoost(QB original) throws IOException {
         QB secondQuery = copyQuery(original);
         if (randomBoolean()) {