- 
Get an open extension
GET https://graph.microsoft.com/v1.0/me?$select=id,displayName,mail,mobilePhone&$expand=extensions 
- 
Create an open extension
POST https://graph.microsoft.com/v1.0/me/extensions 
- 
Update an open extension
PATCH https://graph.microsoft.com/v1.0/me/extensions/{{ExtensionId}}