code: @Override
      public long identity()
      {
          if (tc.isEntryEnabled())
              Tr.entry(tc, "identity", this);
          if (tc.isEntryEnabled())
              Tr.exit(tc, "identity", new Long(_identity));
          return _identity;
      }
docs: Returns the identity of this recoverable unit.
  
  @return The identity of this recoverable unit.