Changes to List transactional emails

added the new optional query request parameter transactionalGroupId

api operation id listTransactionalEmails was added

the response property pagination/nextCursor became required for the status 200

the response property pagination/nextPage became required for the status 200

the response property pagination/perPage became required for the status 200

the response property pagination/returnedResults became required for the status 200

the response property pagination/totalPages became required for the status 200

the response property pagination/totalResults became required for the status 200