Writing to a chunked UndertowOutputStream when the client as disconnected results in an expected IOException: "Broken pipe". Closing the stream throws another IOException: "UT000029: Channel was closed mid chunk, if you have attempted to write chunked data you cannot shutdown the channel until after it has all been written.", which isn't useful at that point, since the data can't ever be written.

See: http://lists.jboss.org/pipermail/undertow-dev/2015-January/001094.html