Changes to Register a webhook endpoint

added the optional property retryAfterSeconds to the response with the 400 status

the response property statusCode became optional for the status 400

response property message list-of-types was widened by adding types array to media type application/json of response 400

added the optional property code to the response with the 400 status

added the optional property error to the response with the 400 status

added the optional property remaining to the response with the 400 status

added the optional property required to the response with the 400 status

added the optional property resetAt to the response with the 400 status

endpoint added