fix for "Can not start an object, expecting field name (context: Obje…

…ct)"

Signed-off-by: Mikhail Khludnev <[email protected]>

src/main/java/com/o19s/es/ltr/feature/store/StoredLtrModel.java

@@ -197,6 +197,11 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         return builder;
     }
 
+    @Override
+    public boolean isFragment() {
+        return false;// since toXContent already have enclosing start/endObject braces
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;