title: Java Enum referencing another enum
body: <p>I would like to be able to define an Enum class that would include another Enum as well as its own values.  For example, :</p>
  
  <pre><code>public enum A {
      A1, A2, A3;
  }
  
  public enum B{
      B1, B2, ...(somehow define references to all values in enum A)
  }
  </code></pre>
  
  <p>such that any values contained in enum B must be either defined initself (such as B1, B2) or any values of enum A.</p>
  
  <p>Thanks,</p>