exception in hashedwheelTimer
Exception in thread "pool-2-thread-1" java.lang.NullPointerException
        at io.netty.util.HashedWheelTimer$HashedWheelBucket.addTimeout(HashedWheelTimer.java:625)
        at io.netty.util.HashedWheelTimer$Worker.transferTimeoutsToBuckets(HashedWheelTimer.java:411)
        at io.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:368)
        at java.lang.Thread.run(Thread.java:744)
