Tried to compile this on my system, and I encountered one issue. In the pom file the path to dot is hardcoded as <dotExecutable>/usr/local/bin/dot</dotExecutable>. Removing this line solved it for me. I imagine anyone that has set up dot in /usr/local/bin also would have that in their path, deeming this unecessary?
Other than that it compiled fine, using openjdk-11 and maven 3.6.0 on an arch linux based system. I noticed that one dot file and a few png's were marked as updated in the repository, which is perhaps ideally not necessary as a default action