Static code analysis: potential lock collisions BaseTransactionManagerDelegate#findLock - interned string used as a lock

CID-17577: Bad choice of lock object - Potential lock collisions

at class BaseTransactionManagerDelegate[9] at method findLock.

string_literal: The string literal "__LOCKS_MAP" is an interned string.
  interned_string_lock: Locking on an interned string can cause unexpected locking collisions with third party code.
  Instead of using "__LOCKS_MAP" as a lock, create a final field of type Object which is only used as a lock.

Explanation at description of JBTM-2758

[9] https://github.com/jbosstm/narayana/blob/master/ArjunaJTS/integration/src/main/java/com/arjuna/ats/jbossatx/BaseTransactionManagerDelegate.java#L350