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