It's too bad they are using Gradle and Intellij, used both before, went back to Maven and Eclipse. Personal preference I guess.
Gradle, however, is a dumpster-fire of footguns and obtuse and non-debug-able DSLs.
For small projects, it works fine, as long as the complexity doesn't grow beyond a certain point for the small project (aka, doesn't grow to a big project), and is maintained by the same person.
For a large project, i do not like gradle at all. Maven is a much better build tool, since standardization is the best thing since sliced bread.