code: public Future<Void> commit(){
          if(!(delegate instanceof PgTransaction)){
              throw new IllegalStateException("Not in transaction");
          }
          Future<Void> commit = Future.future();
          ((PgTransaction) delegate).commit(commit);
          return commit;
      }
docs: Commits a transaction.
  @return a <code>Future</code> that completes when the transaction has been committed.
  @throws IllegalStateException if not called <code>beginTransaction</code> before.