Change the default value of targetVolume in G4DebuggingTools/src/VolumeDebugger.h from CALO::CALO to empty string
In this way the whole geometry Atlas::Atlas will be taken into account by the VolumeDebugger (and not only the CALO) and by default the whole geometry will be dumped in the gdml file.
Tested plugging the generated gdml file into FullSimLight