Handle missing type correctlyWhen communicating with an old version, the length of the receivedpacket will be shorter than the byte array. Now, `FileLockPacketPayload`only reads the type when it has been received and returns UNKNOWN if ithas not. Previously, it would have worked by accident because the lastbyte was zero which corresponds to the ordinal number of UNKNOWN.
Make file lock packet type explicit`FileLockCommunicator` now includes an additional byte that representsthe `FileLockPacketType` when sending packets to other processes.`DefaultFileLockContentionHandler` now checks for the`LOCK_RELEASE_CONFIRMATION` type instead of interpreting any packet fora lock for which it already has received a packet as a lock releaseconfirmation.Adding the additional byte will be ignored by old versions which onlyread the first 9 bytes. New versions can still read packets from oldversions that do not include the byte. They use the `UNKNOWN` type inthis case. Thus, this protocol change is backwards compatible.