Naming conventions on inner classes promote consistency in your app and make the code easier to read and maintain.
Apex inner classes
Pattern. Use a regular expression to define the validation pattern for your class names.
Hint. Add a hint to be displayed when a detection is flagged, in order to give developers a tangible example of a name that suits naming convention. (Warning: the hint is not validated, make sure it matches your validation pattern before adding it).
This rule will not fire on test classes