Steps to replicate

1. Create a user
2. Create 5 group (a,b,c,d,e)
3. Add the user into the 5 group
4. Run this URL "<server base url>/rest/usermanagement/1/user/group/direct?username=HereUser@Name.com&start-index=2&max-results=2&expand=group

Observed Behavior

MySQL will give you a,b,c,d
The rest response will be: d,a

Expected Behavior

The rest response should be c,d