Mark SearchSourceBuilder as ToXContentObject (#24795)

SearchSourceBuilder#toXContent prints out a complete object, hence it should implement ToXContentObject

Author: javanna

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

@@ -32,6 +32,7 @@
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.unit.TimeValue;
 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.index.query.QueryBuilder;
@@ -69,7 +70,7 @@
  *
  * @see org.elasticsearch.action.search.SearchRequest#source(SearchSourceBuilder)
  */
-public final class SearchSourceBuilder extends ToXContentToBytes implements Writeable {
+public final class SearchSourceBuilder extends ToXContentToBytes implements Writeable, ToXContentObject {
     private static final DeprecationLogger DEPRECATION_LOGGER =
         new DeprecationLogger(Loggers.getLogger(SearchSourceBuilder.class));
 
@@ -1098,12 +1099,6 @@ public void parseXContent(QueryParseContext context) throws IOException {
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject();
-        innerToXContent(builder, params);
-        builder.endObject();
-        return builder;
-    }
-
-    public void innerToXContent(XContentBuilder builder, Params params) throws IOException {
         if (from != -1) {
             builder.field(FROM_FIELD.getPreferredName(), from);
         }
@@ -1199,7 +1194,7 @@ public void innerToXContent(XContentBuilder builder, Params params) throws IOExc
 
         if (aggregations != null) {
             builder.field(AGGREGATIONS_FIELD.getPreferredName(), aggregations);
-            }
+        }
 
         if (highlightBuilder != null) {
             builder.field(HIGHLIGHT_FIELD.getPreferredName(), highlightBuilder);
@@ -1232,6 +1227,8 @@ public void innerToXContent(XContentBuilder builder, Params params) throws IOExc
         if (collapse != null) {
             builder.field(COLLAPSE.getPreferredName(), collapse);
         }
+        builder.endObject();
+        return builder;
     }
 
     public static class IndexBoost implements Writeable, ToXContent {

core/src/test/java/org/elasticsearch/search/builder/SearchSourceBuilderTests.java

@@ -63,7 +63,7 @@ public void testFromXContent() throws IOException {
         assertParseSearchSource(testSearchSourceBuilder, createParser(builder));
     }
 
-    private void assertParseSearchSource(SearchSourceBuilder testBuilder, XContentParser parser) throws IOException {
+    private static void assertParseSearchSource(SearchSourceBuilder testBuilder, XContentParser parser) throws IOException {
         QueryParseContext parseContext = new QueryParseContext(parser);
         if (randomBoolean()) {
             parser.nextToken(); // sometimes we move it on the START_OBJECT to