Basically, you can think of it as a tool that checks, whether you're source files are carrying proper license headers. Almost any non-trivial organization has a policy for license headers. In the case of the Apache Software Foundation (ASF), this is the ASF Source Header and Copyright Notice Policy.
Rat can be found http://incubator.apache.org/rat/. In other words, it is an incubating Apache project: Has been preliminarily accepted by the ASF, but not finally.
Because it makes running RAT trivial. Basically, you just
add the plugin to the build/plugins
section
of your POM and run mvn rat:check
. Using RAT
cannot be simpler.
Set the configuration parameter "excludeSubProjects" to false.