[keycloak-user] Backend to backend communication through REST with Keycloak protected backends

I have two webapps. Each has frontend(AngularJS) and backend(Java). Each frontend has it's own public access type configuration keycloak.json file. Each backend has it's own bearer-only access type configuration keycloak.json file. Each frontend app is working fine with it's own backend. My task is make REST call to each other(backend to backend). How could I achieve that? Because on each backend REST sevices are protected by checking token validity and if you try to use it "Token issuer" error will happen.