Fetch all PermissionsGroups, including a count of the number of :members in that group. This API requires superuser or group manager of more than one group. Group manager is only available if advanced-permissions is enabled and returns only groups that user is manager of.

Optional query parameter tenancy can be used to filter groups:

• tenancy=external: Returns only tenant groups (where is_tenant_group = true)
• tenancy=internal: Returns only non-tenant groups (where is_tenant_group = false)
• No tenancy parameter: Returns all groups (default behavior)