The serverConfig Mojo parameter is described as
The path to the server configuration to use.
However, when specifying a path like
there is an exception
This is inconvenient. Users should be able to override the default configurations from a WildFly distribution. E.g. the wildfly-maven-plugin could simply copy the file specified in serverConfig to $JBOSS_HOME/standalone/configuration.
As a workaround, I now unpack WildFly with the maven-dependency-plugin, copy my configuration with maven-resources-plugin and add the jbossHome parameter to wildfly-maven-plugin, all of which is rather verbose.