I checked into this further, it is possible to re-implement ResourceFactoryImpl with this:
and then in ExtendedResourceHandlerImpl constructor do:
this.resourceFactory = new ExtendedResourceFactoryImpl(defaultHandler);
This would allow me to change which mapping files are being loaded. It's a copy/paste of those two classes in their entirely because of how they are written in 4.2.2.Final. (I see that they were refactored in 4.3.3). But instead, I think i will just copy over everything from /META-INF/richfaces/staticResourceMapping/Packed.properties into my user configured mapping file defined in web.xml
@ConfigurationItem(names = "org.richfaces.resourceMapping.mappingFile")
Do you see any problems with that?
Sounds reasonable, let us know how it works out, and if ther are any further extension points that need to be provided.