Changes to Add subscribers to list

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

added the optional property issues to the response with the 401 status

added the optional property issues to the response with the 404 status

added the optional property issues to the response with the 500 status

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

added the optional property retryable to the response with the 401 status

added the optional property retryable to the response with the 404 status

added the optional property retryable to the response with the 500 status

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

added the optional property code to the response with the 401 status

added the optional property code to the response with the 404 status

added the optional property code to the response with the 500 status

the response property success became optional for the status 400

the response property success became optional for the status 401

the response property success became optional for the status 404

the response property success became optional for the status 500

endpoint added