Trigger Jet/Met: Removing Trigger.usexAODFlowElements flag and migrating fully to xAODtype FlowElements (ATR-24619)
After validation with usexAODFlowElements=True/False
which showed no differences, making changes introduced in !48491 (merged) permanent: Fully migrating HLT MET and Jet trigger code to using xAODType FlowElements.