code: function (callback) {
          var conn = this.connection(),
              id = this._id; // use the raw ID object
  
          // prevent new transactions from using this connection.
          this.disconnect();
  
          // if commit was called with no active conn, it implies, no transact action
          // was called. as such it is an error.
          if (!conn) {
              // allow one pseudo commit even without connection, so that programmatic call of repeated commits or
              // rollbacks can be trapped.
              // note that the absence of `_id` indicates that a `.disconnect` was called.
              return callback && callback(id ? null : new AdapterError(AdapterError.TRANSACTION_UNINITIATED_ROLL));
          }
  
          conn.rollback(function (error) {
              // try releasing the connection.
              // if that fails then treat it as a major error.
              try {
                  conn.release();
              }
              // if there was an error during release, set that as the main error.
              catch (err) {
                  !error && (error = err);
              }
  
              // disassociate the connection from transaction and execute callback
              Transaction.disassociateConnection(conn);
              callback && callback(error);
          });
      }
docs: Rollback the transaction
  @param {function} callback - receives `error`