@Override
  protected ResultMetadata convert(RequestStatusMetaData requestStatusMetaData) {
    if (requestStatusMetaData == null) {
      return null;
    }

    throw new UnsupportedOperationException();
  }
Convenience method to create a result for invalid requests.

@param msg  message indicating why the request is invalid

@return  a request with a 400 status and msg set
ambari-server/src/main/java/org/apache/ambari/server/api/handlers/QueryCreateHandler.java