Add weights vector to EventHeader and constant for storing them

edm4hep.yaml

@@ -150,6 +150,8 @@ datatypes:
       - int32_t runNumber      //run number
       - uint64_t timeStamp     //time stamp
       - float weight       // event weight
+    VectorMembers:
+      - double weights       // event weights in case there are multiple. **NOTE that weights[0] might not be the same as weight!** Event weight names should be stored using the edm4hep::EventWeights name in the file level metadata.
 
 
   edm4hep::MCParticle:

include/edm4hep/Constants.h

@@ -22,6 +22,7 @@
 namespace edm4hep {
 static constexpr const char* CellIDEncoding = "CellIDEncoding";
 static constexpr const char* EventHeaderName = "EventHeader";
+static constexpr const char* EventWeights = "EventWeightNames";
 } // namespace edm4hep
 
 #endif // EDM4HEP_CONSTANTS_H