I noticed that I don't get any build errors or warnings with unused imports.
I thought there is a checkstyle plugin running as part of Apache reports.
But there isn't.
There is a plugin here: http://maven.apache.org/plugins/maven-checkstyle-plugin/index.html
I think it reveals a lot of useful information. Doesn't mean we fix all of it. But its very helpful.
It may also generate a nice report:
Which can be useful once more people work on code, so you don't need to review syntax and code smells in every PR manually.