title: How to use void Subject in RxJava2?
body: <p>I've managed to create it this way:</p>
  
  <pre><code>private final PublishSubject&lt;Void&gt; subject = PublishSubject.create();
  </code></pre>
  
  <p>But how to pass value to it in <code>onNext(T t)</code>? I can't pass null to it, cause it will throw an exception. <code>onComplete</code> isn't an option too.</p>