RxJava + Websocket - How to add Observable to Websocket listener?

I have a ViewModel that is observing a RxJava Observable in my MainRepo class. I am trying to get my WebsocketListener in the MainRepo class to emit events, but I'm unsure how to do so.

MainRepo class:

private WebSocket ws;

public void createWsConnection() {
        Request request = new Request.Builder()
                .url(Constants.WEBSOCKET_ENDPOINT)
                .addHeader(Constants.WEBSOCKET_HEADERS_KEY, Constants.USER_ID)
                .build();

        OkHttpClient client = new OkHttpClient
                .Builder()
                .pingInterval(30, TimeUnit.SECONDS)
                .build();

        this.ws = client.newWebSocket(request, webSocketListener);
    }

This is where I'm confused. I don't know how I would use the websocket with the RxJava observable.

public Observable<String> createListener(){
        return Observable.create(new ObservableOnSubscribe<String>() {
            @Override
            public void subscribe(@NonNull ObservableEmitter<String> emitter) {
                 //I don't know what to put here in order to emit messages
                 //back to my ViewModel class using the websocket listener
            }
        });
    }

The websocket listener:

 private WebSocketListener webSocketListener = new WebSocketListener() {

        @Override
        public void onOpen(@NotNull WebSocket webSocket, Response response) {
            Timber.d("Ws connection opened...", response.toString());
        }

        @Override
        public void onClosing(@NotNull WebSocket webSocket, int code, @NotNull String reason) {
            Timber.d("Ws connection closing...");
        }

        @Override
        public void onClosed(@NotNull WebSocket webSocket, int code, @NotNull String reason) {
            Timber.d("Ws connection closed...");
        }

        @Override
        public void onMessage(@NotNull WebSocket webSocket, @NotNull String text) {
            Timber.d("Ws incoming message.");

        }

        @Override
        public void onFailure(@NotNull WebSocket webSocket, @NotNull Throwable t, Response response) {
            Timber.e(t, "Ws connection failure.", response.toString());

        }
    };

A function in the ViewModel class that is observing the Observable in my MainRepo class:

public void connectToWs(){
        mainRepo.createListener()
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Observer<String>() {
            @Override
            public void onSubscribe(@NonNull Disposable d) {
                Timber.d("Subscribed");
            }

            @Override
            public void onNext(@NonNull String s) {
                Timber.d("Message: " + s);
            }

            @Override
            public void onError(@NonNull Throwable e) {
                Timber.e(e, "Something went wrong.");
            }

            @Override
            public void onComplete() {
                Timber.d("On complete.");
            }
        });
    }

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