NOT FOR MERGE - rescale DeFT layer IDs to start at 0

Pr/PrKernel/include/PrKernel/PrFTZoneHandler.h

@@ -33,7 +33,11 @@ namespace FTZoneCache {
     PrFTZoneHandler( DeFT const& ftDet ) {
 #ifdef USE_DD4HEP
       auto func = [this]( const DeFTLayer& layer ) {
-        const auto id = layer.layerID();
+        // NOT FOR MERGE
+        // In DetDesc Ids number from 0, but with DD4HEP seem to start at 4 .... ??
+        // This should be fixed at source in Detector but for now just correct here.
+        const auto id = layer.layerID() - 4;
+        // NOT FOR MERGE
         // fixme
         DetectorSegment seg( 0, layer.globalZ(), layer.dxdy(), layer.dzdy(), 0., 0. );
         const auto      xmax = 0.5f * layer.sizeX();