Similarly to what happend to our javascript and c++ we should identify a formatter and apply it to the entire java codebase. And make sure it runs on every check in.

snorp linked to this plugin which seems promising: https://github.com/diffplug/spotless (with the google-java-format)

This change adds a new lint android-format which enforces formatting of Java
code using google-java-format.

To run the lint simply run:

./mach lint -l android-format

This command also support automatically fixing all errors running by adding
--fix:

./mach lint -l android-format --fix

This change also removes all the formatting-related checkstyle checks which are
now implicitly enforced by the formatter.

https://hg.mozilla.org/mozilla-central/rev/a0a60d0f61a5
https://hg.mozilla.org/mozilla-central/rev/1fa64c7fe170