Over 30 possibilities for NPE's when Transaction/SubTransaction of Availability is null

[T.Doenz]

All over the native implementation of CAPI-3, EntryLockedExceptions are thrown when containers or entries are locked. Usually an instance of Availability is used to get the ID's of the Transaction and SubTransaction that holds the lock and pass them to the exception constructor. As the tx and stx field of Availability can be null, an NPE is thrown when the ID's are accessed like in the following typical example:

throw new EntryLockedException(availability.getTx().getId(), availability.getSubTx().getId());

[T.Doenz]

see ticket #33 which describes several examples where such an NPE occurred

[T.Doenz]

The bug included, in addition to EntryLockedException and Availability objects, also ContainerLockedExceptions and LockResult objects.