Building verison 5.0.2 with Oracle Java 8 fails, at least on Ubuntu 15.04.
One reason is the new "doclint" that forces your JavaDoc to be W3C HTML 4.01 conform (http://blog.joda.org/2014/02/turning-off-doclint-in-jdk-8-javadoc.html).
After correcting this, I get errors in the last module (PIPE-gui) about incompatible types (incompatible types: java.lang.Object cannot be converted to uk.ac.imperial.pipe.models.petrinet.Transition).
I haven't looked into this because in the failed test are method calls that always seem to return ?null?
and I got it compiled with Java 7.

I would have uploaded my maven output but GitHub says I have no permission.