The DataClass rule should also disallow overriding equals or hashcode.

[Whathecode]

The main reason to enable the DataClass rule is to have predictable equals and hashcode implementations for classes extending from a base class, i.e., value comparisons instead of reference equality.

However, even when the rule passes, extending implementations may still override equals and hashcode therefore potentially violating the intended/expected behavior.

Therefore, it would make sense for this rule to also inhibit overriding these methods. We could also consider giving the rule a better name to clarify its intent.