Notification of disconnection from target VM.
May be caused by normal termination of a VM,
VM termination by uncaught exception or other error,
debugger action (VirtualMachine.dispose() or
VirtualMachine.exit(int)) or by external events
(for example, target process termination by the
operating system, transport termination, etc).
If the target VM terminates before the disconnection, this event
will be preceded by a VMDeathEvent.