When creating an RHSSO Role Check Policy and adding a client role to the policy it offers the following description of client:
Client of the role. When this is not defined, this policy uses the 'aud' claim as the client.
The default behavior does not appear to be accurate as leaving the client blank results in the following error log in apicast:
2019/01/25 17:23:42 [debug] 21#21: *43 [lua] keycloak_role_check.lua:141: match_client_roles(): Client 'nil' was not found in the access token.
Along with the error log, the role check does not actually function when using blacklisting, since the JWT will not have the correct client ("nil").
This behavior should either be fixed so it works, or removed from the description since liquid can be used if that behavior is desired.