The parent parameter is ignored if it passed, as it is always set to the
The inline_generator and constraint parameters are also ignored. This
class provides its own default inline generator subroutine reference.
This class overrides the message_generator default if none is provided.
Finally, this class requires an additional parameter, methods. This must be
an array reference of method names which the constraint requires. You can also
pass a single string and it will be converted to an array reference
Returns an array reference containing the methods this constraint requires.