rx problem a guy was having on slack. put into a gist because the code was formatted badly. An attempt to make the code more readable.

CallToApi.java

Interceptor addHeadersInterceptor = chain -> {
            
            if (tokenInvalid){
                String token = getToken()); //If multiple call stays here blocked.
            }
          };

public String getToken() {
        
        requestNewToken();
        return tokenSubject.filter(token -> token != null).toBlocking().first();
}

private void requestNewToken() {

        tokenDisposable = Observable.create((ObservableEmitter<String> emitter) -> {
           try {
                  String token = getNewToken();
                  if (!emitter.isDisposed()) {
                      emitter.onNext(token);
                  }
               } catch (Exception error) {
                  
                  if (!emitter.isDisposed()) {
                      emitter.onError(error);
                  }
            }
        }).retryWhen(//Got some condition here to handle some exceptions)
                        .subscribe(token -> { tokenSubject.onNext(token); });
}