One the 2.0 branch, run mvn jetty:run and shut it down.
After this, git status reports an untracked src/main/webapp/build/ directory that contains a stats.json file. I would expect no untracked files to appear by running the project.
I would recommend putting that file somewhere inside /target so that it's automatically ignored. As an alternative, the file could also be listed in .gitignore, but I see that as a less user-friendly option since stats.json is really just an implementation detail that a typical user never needs to see. If only adding it to .gitignore, then mvn clean should also be updated to remove the file.