"queryText": "GOOGLE_ASSISTANT_WELCOME",
      "action": "input.welcome",
      "fulfillmentMessages": [
        {
          "text": {
        "text": [
          "[{"type":"simple_response","platform":"google","textToSpeech":"Hello"}]"
        ]
          }
        }

List<String> texts = new ArrayList<>();
    texts.add( "Foo" );
    message.setText( new GoogleCloudDialogflowV2IntentMessageText().setText( texts ));

"fulfillmentMessages": [
        {
          "text": {
        "text": [ "Foo" ]
          }
        }

MalformedResponse: Failed to parse Dialogflow response into AppResponse because of empty speech response"