code: @Override
      public String getGlobalId() {
  
          if (_globalId == null) {
              _globalId = Util.toHexString(getXid().getGlobalTransactionId());
          }
  
          return _globalId;
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.tx.remote.DistributableTransaction#getGlobalId()