Azure AD identity mapping in custom graph connectors

Hi Team,

I have developed Microsoft custom graph connector (external data source is BrainShark) using beta API's , I would like to understand how we can achieve Azure AD identities mapping in custom connectors when creating externalItem and add them in ACL. 

With build in connectors this configuration is available with not for custom connectors. 

Any suggestions would be greatly appreciated. 

Thanks,

Dhananjay