It searches for CamelCase identifiers that are made of seven or more "terms", where each term is a capital letter followed by one or more lowercase letters.

E.g., ProjectPotatoLoginPageBuilderFactoryObserver.

(Disclaimer: I just made it up. Not an actual Google project name.)

"lang: java" is not a part of regexp; just a Google code search extension that searches for Java.

This searches for camelcase identifiers with at least 7 words.