For what I see, there's not too many supportive documentations out there that will demonstrate how provision AD group membership with the ICF connector using OpenIDM.
The use of the special ldapGroups attribute is not explained anywhere in the Integrators guides to to the date of this blog. This quick blog identifies the tasks required to provision AD group membership from OpenIDM to AD using the LDAP ICF connector.
However this doesn't really explain what ldapGroups actually does and there's no real worked example of how to go from an Assignment to ldapGroups to an assigned group in AD. I wrote up a wiki article for my own reference: AD group memberships automatically to users
This is just my view, others may disagree, but I think the implementation experience could be improved with some more documentation and a more detailed example here.