I see you are using Mendix 7.22, which has REST functionality built in. Why would you use the RestServices module?
Hi,
You can get rid of the error by importing the community commons module. That exclusive split is using a rule that exists in the community commons module. If you dont want to import community commons, you can change the split to use an expression that checks for an empty string instead. I recommend just downloading community commons.
https://appstore.home.mendix.com/link/app/170/Mendix/Community-Commons-Function-Library
Hope this helps!
Have you tried updating your community commons module ?