List Refund Reasons

Retrieve a list of rules in a promotion. The type of rules retrieved depend on the value of the `rule_type` path parameter: - If `rule_type` is `rules`, the promotion's rules are retrivied. - If `rule_type` is `target-rules`, the target rules of the promotion's application method are retrieved. - If `rule_type` is `buy-rules`, the buy rules of the promotion's application method are retrieved.