We've now added support to get basic addressbook data when retrieving contact details. Please refer to the following for more information
1. "addressbook" definition in the Schema section
2. Refer to 'fieldsBuddyList' and 'fieldsGroupList' in the data type definition for POST /v1/session for information on how to retrieve addressbook data with the contact ist
3. Refer to 'fields' in the data type definition for GET /v1/groups and GET /v1/contacts for information on how to retrieve addressbook data with the contact and group list