Cannot set package-level log levels in logging servlet

It is possible to set package-level log levels by a GET request to the LoggingServlet like so :

/cms/logging/?ll=org.hippoecm.hst:DEBUG

It is documented at https://documentation.bloomreach.com/library/administration/servlets-in-use.html

This no longer works, presumably since the moving to log4j2.
[edit] This only works if the package is actually set up already in log4j2.xml

The map returned by method LoggingServlet#getLoggerLevelInfosMap does not contain package-level log levels which prevents setting it.