Changes to Update Slack integration

removed the media type text/plain for the response with the status 400

removed the media type text/plain for the response with the status 403

removed the media type text/plain for the response with the status 404

removed the media type text/plain for the response with the status 429

added the media type application/json for the response with the status 400

added the media type application/json for the response with the status 401

added the media type application/json for the response with the status 403

added the media type application/json for the response with the status 404

added the media type application/json for the response with the status 429

removed the media type application/json for the response with the status 400

removed the media type application/json for the response with the status 401

removed the media type application/json for the response with the status 403

removed the media type application/json for the response with the status 404

added the media type text/plain for the response with the status 400

added the media type text/plain for the response with the status 403

added the media type text/plain for the response with the status 404

added the non-success response with the status 429

removed the media type text/plain for the response with the status 400

removed the media type text/plain for the response with the status 403

removed the media type text/plain for the response with the status 404

added the media type application/json for the response with the status 400

added the media type application/json for the response with the status 401

added the media type application/json for the response with the status 403

added the media type application/json for the response with the status 404

the request property channelName became not nullable

the response's body became nullable

added the non-success response with the status 400

added the non-success response with the status 401

added the non-success response with the status 403

added the non-success response with the status 404

endpoint added