According to the spec 'iss' should be:
REQUIRED. Issuer Identifier for the Issuer of the response. The iss value is a case
sensitive URL using the https scheme that contains scheme, host, and optionally, port
number and path components and no query or fragment components
However, we only use realm name. As that's invalid according to the spec (and also the
same iss used for multiple KC servers) I propose we change it to:
<AUTH URL>/realms/<REALM-NAME>
For example:
http://localhost:8080/realms/master