Retrieve merchant custom attribute definition

The key of the custom attribute definition to retrieve. If the requesting application is not the definition owner, you must use the qualified key.

The current version of the custom attribute definition, which is used for strongly consistent reads to guarantee that you receive the most up-to-date data. When included in the request, Square returns the specified version or a higher version if one exists. If the specified version is higher than the current version, Square returns a BAD_REQUEST error.