- Returns an array of structs containing details about all node
- groups. If nodegroup_id_or_name_list is specified, only the
- specified node groups will be queried.
+ Returns an array of structs containing details about node groups.
+ If nodegroup_filter is specified and is an array of node group
+ identifiers or names, or a struct of node group attributes, only
+ node groups matching the filter will be returned. If return_fields
+ is specified, only the specified details will be returned.