[speech-to-text] Customization does not work when using recognizeUsingWebSocket() method #540

// 1) create RecognitionOptions object with customization ID
RecognizeOptions sttOptions = new RecognizeOptions.Builder()
    .customizationId(MY_CUSTOMIZATION_ID).build();
// 2) use websocket interface with these options
sttService.recognizeUsingWebSocket(audioSource, sttOptions, resultCb);

public class WebSocketManager {
    // ...
    private class SpeechToTextWebSocketListener implements WebSocketListener {
        private static final String CUSTOMIZATION = "customization_id";
        // ...
        private String buildStartMessage(RecognizeOptions options) {
            JsonObject startMessage = new JsonParser().parse(new Gson().toJson(options)).getAsJsonObject();
            startMessage.remove(MODEL);
            startMessage.remove(CUSTOMIZATION);
            startMessage.addProperty(ACTION, START);
            return startMessage.toString();
        }
        // ...
    }
    // ...
    private WebSocketCall createConnection(RecognizeOptions options) {
        String speechModel = options.model() == null ? "" : "?model=" + options.model();
        if (options.customizationId() != null) {
            speechModel += "&customization_id=" + options.customizationId();
        }
        Builder builder = new Request.Builder().url(url + speechModel);
        // ...
    }
    // ...
}