jboss.patch.url is a system property used to hold the name of the environment property for specifying the URL where JBoss will read patch library files from.

Example:

$ sh bin/run.sh -c -Djboss.patch.url=file:/C:/jboss/cases/0000000-overriding_class_in_ear/patch-url-classes

If this value is a file URL, then all .zip, .jar files and classes inside will be prepended to the classpath.  Otherwise the URL will be added to the classpath.  If not set then the no patch files will be loaded.