public ResponseStream<GenerateContentResponse> sendMessageStream(String text) throws IOException {
    return sendMessageStream(ContentMaker.fromString(text));
  }
Sends a message to the model and returns a stream of responses.

@param text the message to be sent.
@return an iterable in which each element is a GenerateContentResponse. Can be converted to
    stream by stream() method.
java-vertexai/google-cloud-vertexai/src/main/java/com/google/cloud/vertexai/generativeai/ChatSession.java