title: java.lang.ProcessHandle - compilation error
body: <p>I'm running java 11 and trying to use ProcessHandle</p>
  
  <pre><code>Optional&lt;ProcessHandle&gt; optionalProcessHandle = ProcessHandle.of(Long.parseLong(pid));
  optionalProcessHandle.ifPresent(processHandle -&gt; processHandle.destroy());
  </code></pre>
  
  <p>Getting compilation error:</p>
  
  <pre><code>Error:(184, 39) java: cannot find symbol
    symbol:   class ProcessHandle
    location: package java.lang
  </code></pre>
  
  <p>What am I doing wrong?</p>