https://checkstyle.org/config_misc.html#OuterTypeFilename

Add example for each existing config to show what code is ok and what code cause violation.
Good example is https://checkstyle.org/config_naming.html#AbstractClassName

please play with module/Check by means of https://checkstyle.org/cmdline.html to understand how it works.

PLEASE READ https://github.com/checkstyle/checkstyle/wiki/Good-practice-on-how-to-update-examples