code: @Override
      public boolean accept(Stanza message) {
          if (!message.hasStanzaIdSet()) {
              return false;
          }
  
          if (super.accept(message)) {
              ExtensionElement extension = message.getExtension(ChatStateManager.NAMESPACE);
              String chatStateElementName = extension.getElementName();
  
              ChatState state;
              try {
                  state = ChatState.valueOf(chatStateElementName);
                  return (state == ChatState.active);
              }
              catch (Exception ex) {
                  return false;
              }
          }
  
          return true;
      }
docs: From XEP-0333, Protocol Format: The Chat Marker MUST have an 'id' which is the 'id' of the
  message being marked.<br>
  In order to make Chat Markers works together with XEP-0085 as it said in
  8.5 Interaction with Chat States, only messages with <tt>active</tt> chat
  state are accepted.
  
  @param message to be analyzed.
  @return true if the message contains a stanza Id.
  @see <a href="http://xmpp.org/extensions/xep-0333.html">XEP-0333: Chat Markers</a>