columnar::MetAssociationDef Node1 columnar::MetAssociationDef + idName   Node2 columnar::RegularContainer Id< xAOD::MissingETAssociation, xAOD::MissingETAssociationMap > + isContainerId + regularObjectId + variantObjectId + regularColumnAccessorArray + isMutable + perEventRange + perEventId   Node2->Node1