@Override
            public List<String> getHeaderValues(String name) {
                return Collections.emptyList();
            }
We *spy* (not *mock*) the {@link HttpsJwks} instance because we want to have it
_partially mocked_ to determine if it's calling its internal refresh method. We want to
make sure it *doesn't* do that when we call our getJsonWebKeys() method on
{@link RefreshingHttpsJwks}.
clients/src/test/java/org/apache/kafka/common/security/oauthbearer/internals/secured/RefreshingHttpsJwksTest.java