This should be the mail address or the group in the source AD or AAD provider. Example: jamal@contoso.com Team Services will communicate with the source provider to fill all other fields on creation.
OptionalstorageOptional: If provided, we will use this identifier for the storage key of the created group
Use this type to create a new group using the mail address as a reference to an existing group from an external AD or AAD backed provider. This is the subset of GraphGroup fields required for creation of a group for the AAD and AD use case.