code: static boolean isRegistered(Object value) {
          Map<Object, Object> m = getRegistry();
          return m != null && m.containsKey(value);
      }
docs: <p>
  Returns <code>true</code> if the registry contains the given object.
  Used by the reflection methods to avoid infinite loops.
  </p>
  
  @param value The object to lookup in the registry.
  @return boolean <code>true</code> if the registry contains the given
  object.