@Override
 public void doXContent(XContentBuilder builder, Params params) throws IOException {
   builder.startObject(getName());
   builder.field(fieldName);
   XContentParser parser = XContentFactory.xContent(functionBytes).createParser(functionBytes);
   builder.copyCurrentStructure(parser);
   builder.field(DecayFunctionParser.MULTI_VALUE_MODE.getPreferredName(), multiValueMode.name());
   builder.endObject();
 }