When the HC creates the configuration ops for a domain server, it includes ops to add system-property resources for all relevant properties from domain.xml and host.xml. This includes the ones with boot-time=true set. But that setting means the property is set as part of the command used to launch the server process JVM. It doesn't need to be in the server config.

This is minor as I've not heard of any reports of it doing any harm. Note the value attribute of the resource will be the clear text value. However, an admin with perms to read the resource would also have perms to read the platform mbean resources, which provide all system properties.