title: java.util.stream.Collectors with EnumSet Stream
body: <p>I'm trying to use in place of bitmask below is the code </p>
  
  <pre><code>public static Set&lt;Amenities&gt; fromBitFlags(int bitFlag) {
      return ALL_OPTS.stream().filter(a -&gt; (a.ameityId &amp; bitFlag) &gt; 0).collect(Collectors.toSet());
  }
  </code></pre>
  
  <p>I would like to return EnumSet instead of a plain set(dont want to loose out on EnumSet's usefulness just because of casting). </p>
  
  <p>Need some directions on how to create a Custom Collector to collect EnumSet.</p>