File not found when loading external resource in a jar file

As title, For cases like a resource in located in a jar file
We use jetty embedded as container and we setup manually the resource location to be into jar files (new PathResource(new URL(JarResource.newJarResource(new PathResource(uiURL))))

It later however fail trying to load resources. The offending code is in the HtmlTreeBuilder class where a URL is always converted to be a File. The proposed patch uses url.openStream instead and solves the issue.

Test case : https://github.com/vimpagliazzo/zk-loader-testcase
Do a "mvn install" on the root project, then "cd zk-loader-runner" and run mvn exec:java -Dexec.mainClass="Runner".
And you can see the error open http://localhost:8090/index.zhtml