...
TJ: getHistogramLevel() should determine whether hists are filled.
NS: Encountered case in geometry of sidaug05 where layers in reverse order of subdetector. Always order radius in increasing radius, z. In VertexBarrelSupport, foam layer is layer 0 and aluminum layer is layer 1 and has smaller r.
TJ: On fixed cone clusterer, RC added some methods, but names were kind of unclear.
RC: Just temporary until agree on common interface.