Should fix the compilation failure observed at http://atlas-computing.web.cern.ch/atlas-computing/links/distDirectory/gitwww/PRODUCTIONWebArea/ardoc_web_areamain64BC7G11AthenaOpt/ARDOC_Log_2023-11-07T2101/InnerDetector_InDetRecTools_SiZvertexTool_xk.html
cc @christos @elmsheus @emoyse