Thanks Lynn/Sergio
For background, the "working with out defining the log manager bootclasspath " instances are in our Openshift environment running as Docker images.
The ones that need the extra classpath config for APM to work are in our traditional on-prem standalone builds.
I asked our JBOSS SME yesterday regarding the JBOSS build that works with APM with no explicit logmanager boot classpath configured.
There is a difference in the 2 JBOSS builds.
The "working" one in Openshift defines the log manager in a file called "/opt/eap/custom_modules/org/jboss/logmanager/ext/main/module.xml"
The SME told me - ". With custom module definition we initialize logging system and libraries statically before Java Agent startup"
which implies that the logging system is pre-loaded and available in time so APM agent can use it.
Are you aware of this mechanism to define the log manager ? This seems to work with no extra config needed.