T call() throws IOException, RegistryException {
    String apiRouteBase = "https://" + registryEndpointRequestProperties.getServerUrl() + "/v2/";
    URL initialRequestUrl = registryEndpointProvider.getApiRoute(apiRouteBase);
    return call(initialRequestUrl);
  }
Makes the request to the endpoint.

@return an object representing the response, or {@code null}
@throws IOException for most I/O exceptions when making the request
@throws RegistryException for known exceptions when interacting with the registry
jib-core/src/main/java/com/google/cloud/tools/jib/registry/RegistryEndpointCaller.java