columnar::ContainerId::met Node1 columnar::ContainerId::met + idName Node3 columnar::ContainerId ::met1 + idName Node1->Node3 Node2 columnar::ContainerId ::regularCIBase< xAOD ::MissingET, xAOD::MissingETContainer > + isContainerId + regularObjectId + regularColumnAccessorArray + isMutable + perEventRange + perEventId Node2->Node1