Client: Make the query builder nullable in filteredQuery.

Close #7398

src/main/java/org/elasticsearch/index/query/FilteredQueryBuilder.java

@@ -40,10 +40,10 @@ public class FilteredQueryBuilder extends BaseQueryBuilder implements BoostableQ
     /**
      * A query that applies a filter to the results of another query.
      *
-     * @param queryBuilder  The query to apply the filter to
+     * @param queryBuilder  The query to apply the filter to (Can be null)
      * @param filterBuilder The filter to apply on the query (Can be null)
      */
-    public FilteredQueryBuilder(QueryBuilder queryBuilder, @Nullable FilterBuilder filterBuilder) {
+    public FilteredQueryBuilder(@Nullable QueryBuilder queryBuilder, @Nullable FilterBuilder filterBuilder) {
         this.queryBuilder = queryBuilder;
         this.filterBuilder = filterBuilder;
     }
@@ -68,8 +68,10 @@ public class FilteredQueryBuilder extends BaseQueryBuilder implements BoostableQ
     @Override
     protected void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(FilteredQueryParser.NAME);
+        if (queryBuilder != null) {
             builder.field("query");
             queryBuilder.toXContent(builder, params);
+        }
         if (filterBuilder != null) {
             builder.field("filter");
             filterBuilder.toXContent(builder, params);

src/main/java/org/elasticsearch/index/query/QueryBuilders.java

@@ -395,7 +395,7 @@ public abstract class QueryBuilders {
      * @param queryBuilder  The query to apply the filter to
      * @param filterBuilder The filter to apply on the query
      */
-    public static FilteredQueryBuilder filteredQuery(QueryBuilder queryBuilder, @Nullable FilterBuilder filterBuilder) {
+    public static FilteredQueryBuilder filteredQuery(@Nullable QueryBuilder queryBuilder, @Nullable FilterBuilder filterBuilder) {
         return new FilteredQueryBuilder(queryBuilder, filterBuilder);
     }
 

src/test/java/org/elasticsearch/search/query/SimpleQueryTests.java

@@ -2662,6 +2662,18 @@ public class SimpleQueryTests extends ElasticsearchIntegrationTest {
         }
     }
 
+    @Test // see #7365
+    public void testFilteredQueryWithoutQuery() throws Exception {
+        createIndex("test");
+        ensureYellow("test");
+        indexRandom(true, client().prepareIndex("test", "type1", "1").setSource("field1", "value1"));
+        SearchResponse response = client().prepareSearch()
+                .setQuery(QueryBuilders.filteredQuery(null,
+                        FilterBuilders.termFilter("field1", "value1"))).get();
+        assertSearchResponse(response);
+        assertHitCount(response, 1l);
+    }
+
     @Test
     public void testQueryStringParserCache() throws Exception {
         createIndex("test");