Set conversation message reception

OpenIMClient.getInstance().conversationManager.setConversationRecvMessageOpt(
    new OnBase<String>() {
        @Override
        public void onSuccess(String data) {
            // The request completed.
        }

        @Override
        public void onError(int code, String error) {
            // code and error describe the failure.
        }
    },
    conversationID,
    2
);