Some Jenkins properties are available within Maven via Java system properties, e.g. ${BUILD_NUMBER}. Can we expose useful Perforce properties this way as well, particularly the highest changelist found when synching the workspace prior to building? I think the best place for this is the checkout() method, local variable "newestChange", right after the build counter is updated. You could do something like this:

System.setProperty("PERFORCE_CHANGELIST", String.valueOf(newestChange));