How to get custom attributes from claims?

Question

This document describes steps to select user attributes to appear in claims token:

You should now see ShoeSize in the list of attributes collected during the sign-up journey, and see it in the token sent back to your application.

After following above steps custom attributes do not appear in the token sent back to my application. What am I doing wrong?

See also this stackoverflow ticket

Answer 1

The problem was that the properties were not populated with values. Apparently if a value is null it is not returned. Seems an odd behavior given that many other (unrelated) properties on the response object are null, empty, or undefined.