Comment #2 on issue 152 by jean.deruelle: NullPointerException on ACK Retransmission
http://code.google.com/p/sipservlets/issues/detail?id=152
This issue was updated by revision d2baec160d5d. Backport to master branch (cherry picked from commit 962bd30a7b990d248d13997f2908fc9e48ccdffe)
