Connect Flow Elements to Muon container

Hi all (cc @mhodgkin )

This merge request covers new particle flow objects known as Flow Elements (in the updated EDM) and the linkage of these objects to Muons. This MR only couples charged flow elements to muons via track index matching.

Thanks

Matt

Reconstruction/eflowRec/src/PFMuonFlowElementAssoc.cxx

@@ -114,6 +114,7 @@ StatusCode PFMuonFlowElementAssoc::execute() {
   //   Loop over Neutral FlowElements
   //////////////////////////////////////////////////
   if(m_LinkNeutralFEClusters){
+    ATH_MSG_DEBUG("Experimental: Cluster Linkers between neutral FEs and Muons are used");
     for (const xAOD::FlowElement* FE: *NeutralFEmuonWriteDecorHandle){
       //get the index of the cluster corresponding to the Neutral FlowElements
       size_t FEclusterindex=FE->otherObjects().at(0)->index();
@@ -146,11 +147,14 @@ StatusCode PFMuonFlowElementAssoc::execute() {
   //////////////////////////////////////////////////
   // Add the vectors of the Flow Element Links as decoations to the muon container
   for(const xAOD::Muon* muon: *muonChargedFEWriteDecorHandle){
-    muonChargedFEWriteDecorHandle(*muon)=muonChargedFEVec.at(muon->index());
-
+    muonChargedFEWriteDecorHandle(*muon)=muonChargedFEVec.at(muon->index());    
   } // end of muon loop
-  for(const xAOD::Muon* muon: *muonNeutralFEWriteDecorHandle){
-    muonNeutralFEWriteDecorHandle(*muon)=muonNeutralFEVec.at(muon->index());
+  if(m_LinkNeutralFEClusters){
+    for(const xAOD::Muon* muon: *muonNeutralFEWriteDecorHandle){
+      if(muonNeutralFEVec.size()>0){
+	muonNeutralFEWriteDecorHandle(*muon)=muonNeutralFEVec.at(muon->index());
+      }
+    }
   }
   ATH_MSG_DEBUG("Execute completed successfully");