Need to decide how to implement rechit-cluster association with sharing enabled

[clelange]

The ntupliser curently assumes that sharing is not enabled and therefore a 1-to-1 association between rechits and layer clusters exists: https://github.com/CMS-HGCAL/reco-ntuples/blob/master/HGCalAnalysis/plugins/HGCalAnalysis.cc#L1831-L1851

With sharing enabled, a rechit can be associated to more than one cluster. If we want to preserve this information in the ntuple, we would need to change rechit_cluster2d_ (the variable that stores the index of the associated layer cluster, https://github.com/CMS-HGCAL/reco-ntuples/blob/master/HGCalAnalysis/plugins/HGCalAnalysis.cc#L1917) to a vector of integers.

Any comments or alternative suggestions?

[artlbv]

I guess, in that case one would also need to add a vector like rechit_cluster2d_fraction_ for the corresponding fractions?