Okey, so we’ve found out that the /groupuserpicker?query=[query] endpoint returns users in strange ways.
I’ve figured out that it:
- returns correct results for queries which match “beginning-part” of the
displayName, - does not return results for queries which match “middle-part” of the
displayName, - returns correct results for queries which match both “beginning-part” and “middle-part” of the emailAddress.
The problem is the second bullet-point mentioned above.
Moreover, I’ve found out that it works in the similar way for endpoints like /user/picker/ or /user/search/ - it matches any-part of emailAddress and only-first-part of the displayName.