DesktopConnection implements Closeable, so it is implicitly closed after
its try-with-resources block. Closing the DesktopConnection shutdowns
the sockets, so it is necessary in particular to wake up blocking read()
calls from the controller.
But the controller thread was joined before the DesktopConnection was
closed, causing a deadlock. To fix the problem, join the controller
thread only after the DesktopConnection is closed.
Refs 400a1c69b198103feff9682895529529890c1acc
5cf86ef7ff