title: Method reference notation vs "standard" Lambda notation
body: <p>I was expecting these to be simple drop-in replacements for each other, but they're not. Clearly I'm not understanding the notation.</p>
  <p>Can anyone explain why does that happen?</p>
  <pre><code>playButton.setOnAction(e -&gt; track.play());
  </code></pre>
  <p>Here, compiler is happy with <code>play()</code> having a signature of</p>
  <pre><code>void play()
  </code></pre>
  <p>but here</p>
  <pre><code>playButton.setOnAction(track::play);
  </code></pre>
  <p>it requires</p>
  <pre><code>void play(Event e)
  </code></pre>