caught exception in dispatchImpl

[GZ315200]

Hi
I got this exception in following when I use sendMessageToUser method. the detail of exception message is in the following

java.lang.ClassCastException: com.ullink.slack.simpleslackapi.replies.SlackReplyImpl cannot be cast to com.ullink.slack.simpleslackapi.replies.SlackChannelReply
at com.ullink.slack.simpleslackapi.impl.SlackWebSocketSessionImpl.getIMChannelForUser(SlackWebSocketSessionImpl.java:168)
at com.ullink.slack.simpleslackapi.impl.SlackWebSocketSessionImpl.sendMessageToUser(SlackWebSocketSessionImpl.java:140)
at handler.ReplyMessage$.replayToWithAttachment(ReplyMessage.scala:13)
at handler.SlackMessageSession$.trigger(SlackMessageSession.scala:25)
at handler.SlackBot.$anonfun$listen$1(SlackBot.scala:25)
at com.ullink.slack.simpleslackapi.impl.SlackWebSocketSessionImpl$EventDispatcher.dispatchImpl(SlackWebSocketSessionImpl.java:246)
at com.ullink.slack.simpleslackapi.impl.SlackWebSocketSessionImpl$EventDispatcher.dispatch(SlackWebSocketSessionImpl.java:203)
at com.ullink.slack.simpleslackapi.impl.SlackWebSocketSessionImpl.onMessage(SlackWebSocketSessionImpl.java:1074)
at com.ullink.slack.simpleslackapi.impl.SlackWebSocketSessionImpl.onMessage(SlackWebSocketSessionImpl.java:57)
at org.glassfish.tyrus.core.TyrusSession.notifyMessageHandlers(TyrusSession.java:576)