JWT claim with url in key not processed by Istio

I have setup a RequestAuthentication object which correctly validates incoming JWT tokens, and copies claims to headers where the key is a simple string, e.g. ‘aud’.

However, I have a claim that has the key ‘http://example.com/region’ which is not copied to a header when I specify it in the RequestAuthentication object.

I did this in response to the routing configuration not working when the JWT claim routing did not work.

Below is a snippet of the config I had to match a claim in the VirtualService.

  - name: match jwt
      - headers:
            exact: global```

Below is a snippet of the config I had to copy JWT claims to headers in the RequestAuthentication object

    - header: "jwt-aud"
      claim: "aud"
    - header: "jwt-region"
      claim: 'https://example.com/region'
    - header: "jwt-sub"
      claim: "sub"

Based on the below example contained in the RFC, I think this should work, but I am unsure if I have a syntax problem, or it is unsupported.