code: void closeTransactionalBranch(Xid xid) {
  
          if (this.transactionBinding.getTransactionBindingType() != TransactionBindingType.GlobalTransaction) {
              throw new IllegalStateException("XAConnection not associated to a global transaction");
          }
  
          GlobalTransactionProxy<C> globalTransactionProxy = this.transactionBinding.getEnlistedGlobalTransaction();
          globalTransactionProxy.close();
  
          delistTransaction();
      }
docs: call by the XCAResource when
  {@link javax.transaction.xa.XAResource#end(javax.transaction.xa.Xid, int)}
  is called
  
  @param xid