docs: public void attachSession(List<ServiceInstanceToken> instanceTokens){
          ProtocolHeader header = new ProtocolHeader();
          header.setType(ProtocolType.AttachSession);
  
          String sessionId = connection.getSessionId();
          AttachSessionProtocol protocol = new AttachSessionProtocol(instanceTokens, sessionId);
          connection.submitRequest(header, protocol, null);
  
      }