Failed to submit an exceptionCaught() event

[jknack]

The following warn message occurs sometimes at application shutdown or restart time:

[2017-01-15 18:10:41,255]-[nio-worker-3-5] WARN  io.netty.channel.AbstractChannelHandlerContext - Failed to submit an exceptionCaught() event.
java.util.concurrent.RejectedExecutionException: event executor terminated
	at io.netty.util.concurrent.SingleThreadEventExecutor.reject(SingleThreadEventExecutor.java:836)
	at io.netty.util.concurrent.SingleThreadEventExecutor.offerTask(SingleThreadEventExecutor.java:342)
	at io.netty.util.concurrent.SingleThreadEventExecutor.addTask(SingleThreadEventExecutor.java:335)
	at io.netty.util.concurrent.SingleThreadEventExecutor.execute(SingleThreadEventExecutor.java:761)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:278)
	at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:267)
	at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:296)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:275)
	at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:267)
	at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireExceptionCaught(CombinedChannelDuplexHandler.java:423)
	at io.netty.channel.ChannelHandlerAdapter.exceptionCaught(ChannelHandlerAdapter.java:78)
	at io.netty.channel.CombinedChannelDuplexHandler$1.fireExceptionCaught(CombinedChannelDuplexHandler.java:144)
	at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
	at io.netty.channel.CombinedChannelDuplexHandler.exceptionCaught(CombinedChannelDuplexHandler.java:230)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:296)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:275)
	at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:267)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.exceptionCaught(DefaultChannelPipeline.java:1301)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:296)
	at io.netty.channel.AbstractChannelHandlerContext.notifyHandlerException(AbstractChannelHandlerContext.java:861)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:193)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelUnregistered(AbstractChannelHandlerContext.java:177)
	at io.netty.channel.DefaultChannelPipeline.fireChannelUnregistered(DefaultChannelPipeline.java:826)
	at io.netty.channel.AbstractChannel$AbstractUnsafe$7.run(AbstractChannel.java:752)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasksFrom(SingleThreadEventExecutor.java:394)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:369)
	at io.netty.util.concurrent.SingleThreadEventExecutor.confirmShutdown(SingleThreadEventExecutor.java:693)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:464)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:873)
	at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:144)
	at java.lang.Thread.run(Thread.java:745)