### Question:
AuthenticationMethodRetriever implements RegistryEndpointProvider<Optional<RegistryAuthenticator>> { @Nullable @Override public BlobHttpContent getContent() { return null; } AuthenticationMethodRetriever(
      RegistryEndpointRequestProperties registryEndpointRequestProperties,
      @Nullable String userAgent,
      FailoverHttpClient httpClient); @Nullable @Override BlobHttpContent getContent(); @Override List<String> getAccept(); @Override Optional<RegistryAuthenticator> handleResponse(Response response); @Override URL getApiRoute(String apiRouteBase); @Override String getHttpMethod(); @Override String getActionDescription(); @Override Optional<RegistryAuthenticator> handleHttpResponseException(
      ResponseException responseException);  }### Answer:
@Test public void testGetContent() { Assert.assertNull(testAuthenticationMethodRetriever.getContent()); }