Add source code linter / formatter
Add an automated source code linter / formatter to make sure the code style does not drift. The clear choice seems to be spotless as it offers a Gradle plugin, integrates with various formatters, and provides a healthy amount of configurability.
The more difficult question is going to be which code formatting profile. I think the Eclipse formatter will be the easiest to customize because the exported profile from the Eclipse IDE can be passed right into the tool. We just need to settle on the rules to apply.