title: Create Reads/Writes for Java Enum without Field
body: <p>With the Play Framework's JSON library, how can I create a <code>Reads</code> and <code>Writes</code> for a Java enum without fields?</p>
  
  <p><code>public enum EnumNoFields {
      RED,
      WHITE,
      BLUE
  }</code></p>
  
  <pre><code>implicit val EnumNoFieldsReads: Reads[EnumNoFields] = ?
  implicit val EnumNoFieldsWrites: Writes[EnumNoFields] = ?
  </code></pre>