@Override
  public Response call(String httpMethod, URL url, Request request) throws IOException {
    GenericUrl httpUrl = new GenericUrl(url);
    httpUrl.setScheme("http");
    return super.call(httpMethod, httpUrl.toURL(), request);
  }
Forces sending all requests in plain-HTTP protocol. For testing only.
jib-core/src/test/java/com/google/cloud/tools/jib/registry/PlainHttpClient.java