Using OpenId Connect with Salesforce Identity as the IDP and I am trying to add a custom attribute encoded within the ID token. Is this possible? I can't find any documentation on the topic within Salesforce. I can add it as a custom attribute to the user record that can be retrieved in the userinfo endpoint but trying not require an additional API call for the mobile device and additional attributes pushed to the backend server for identification of the user. Our ID is not the Username (passed in the ID token) as it is mutable.