solved a deadlock situation in XMPPConnection.shutdown() basically by calling socket.close() prior calling (reader|writer).close().

We need to determine if calling reader.close() and writer.close() is still needed. And it's very likely that the last call to socket.close() is now redundant.

The code parts should be dropped in future versions of SMACK if possible, they just remained there after fixing to ensure that this core change doesn't cause any regressions.