System and configuration properties do not have currently same kind of file based alternative as surefire currently provides. This becomes quite handy when number of properties is high or generic cargo config is declared in parent pom and properties are refined later on. Just a warning will be logged if either of the files is defined but doesn't exist just like with surefire. Therefore the logging initialization got a little overhaul as well.
There was already a similar request for ANT but my provided patches only cover Maven plugin.