UserAccessor.addMembership only executable for admin users

[Stefan Baader]

I want to create a user macro which delivers the ability to add users to an existing group.

I tried the macro and it worked fine. But for a standard user the macro does not work.

I found out that this line of code is the reason:

$userAccessor.addMembership($group, $memberuser )

This method can't be executed when logged in as a non-admin-user. Any idea how this can be solved?