title: Cannot convert void to java.lang.Void
body: <p>I'm trying to do the following</p>
  
  <pre><code>interface Updater {
      void update(String value);
  }
  
  void update(Collection&lt;String&gt; values, Updater updater) {
      update(values, updater::update, 0);
  }
  
  void update(Collection&lt;String&gt; values, Function&lt;String, Void&gt; fn, int ignored) {
      // some code
  }
  </code></pre>
  
  <p>but I get this compiler error:</p>
  
  <pre><code>"Cannot convert void to java.lang.Void"
  </code></pre>
  
  <p>That means <code>updater::update</code> cannot be used as <code>Function&lt;String, Void&gt;</code>. </p>
  
  <p>Of course I can't write <code>Function &lt;String, void&gt;</code> and I don't want to change return type of <code>update()</code> to <code>Void</code>.</p>
  
  <p>How do I resolve this problem?</p>