title: Handle empty response with retrofit and rxjava 2.x
body: <p>When using rxjava 1.x i used to return <code>Observable&lt;Void&gt;</code> to handle empty response from retrofit:</p>
  
  <pre><code>@POST( "login" )
  Observable&lt;Void&gt; getToken( @Header( "Authorization" ) String authorization,
                                         @Header( "username" ) String username,
                                         @Header( "password" ) String password );
  </code></pre>
  
  <p>But since rxjava 2.x won't emit anything with <code>Void</code> is there any good practice to handle those empty responses?</p>