DerivationFramework: Restore CHS FlowElements function

A function to schedule production of the CHS PFO FlowElement collection was introduced in !37239 (merged) as a necessary part of the jet building for derivations. It appears to have been accidentally removed by !37631 (merged). This simply restores it so we can make jets out of FlowElements in derivations again.

Tagging @cdelitzs, @mswiatlo, @sawyer.

PhysicsAnalysis/DerivationFramework/DerivationFrameworkJetEtMiss/python/ExtendedJetCommon.py

@@ -126,7 +126,7 @@ def addAntiKt10TruthWZJets(sequence,outputlist):
         addStandardJets("AntiKt", 1.0, "TruthWZ", ptmin=40000, mods="truth_ungroomed_larger", algseq=sequence, outputGroup=outputlist)
 
 def addAntiKt4EMPFlowJetsFE(sequence, outputlist):
-    addCHSPFlowObjectsFE()   # noqa: F821 (FIXME, does not exist)
+    addCHSPFlowObjectsFE()
     addStandardJets("AntiKt", 0.4, "EMPFlowFE", ptmin=10000, ptminFilter=15000, mods="pflow_ungroomed", algseq=sequence, outputGroup=outputlist)
 
 ##################################################################  
@@ -857,7 +857,32 @@ def addCHSPFlowObjects():
             job.jetalg.Tools.append(jtm.jetconstitCHSPFlow)
             extjetlog.info("Added CHS PFlow sequence to \'jetalg\'")
             extjetlog.info(job.jetalg.Tools)
+
 ##################################################################
+# Same as above, but using xAOD::FlowElement instead of xAOD::PFO
+##################################################################   
+def addCHSPFlowObjectsFE():
+    # Only act if the collection does not already exist
+    from RecExConfig.AutoConfiguration import IsInInputFile
+    if not IsInInputFile("xAOD::FlowElementContainer","CHSFlowElements"):
+        # Check that an alg doing this has not already been inserted
+        from AthenaCommon.AlgSequence import AlgSequence
+        job = AlgSequence()
+        from JetRec.JetRecStandard import jtm
+        if not hasattr(job,"jetalgCHSPFlowFE") and not hasattr(jtm,"jetconstitCHSPFlowFE"):
+            from JetRec.JetRecConf import JetToolRunner
+            jtm += JetToolRunner("jetconstitCHSPFlowFE",
+                                 EventShapeTools=[],
+                                 Tools=[jtm.JetConstitSeq_PFlowCHS_FE])
+            # Add this tool runner to the JetAlgorithm instance "jetalg"
+            # which runs all preparatory tools
+            # This was added by JetCommon
+            job.jetalg.Tools.append(jtm.jetconstitCHSPFlowFE)
+            extjetlog.info("Added CHS PFlow (FlowElement) sequence to \'jetalg\'")
+            extjetlog.info(job.jetalg.Tools)
+
+##################################################################
+
 applyJetCalibration_xAODColl("AntiKt4EMTopo")
 updateJVT_xAODColl("AntiKt4EMTopo")
 applyJetCalibration_xAODColl("AntiKt4EMPFlow")