code: private String asJettyFriendlyPath(String path, String name) {
          try {
              new URL(path);
              log.debug("Defer interpretation of {} URL '{}' to Jetty", name, path);
              return path;
          } catch (MalformedURLException e) {
              //Expected. We've got a path and not a URL
              Path p = Paths.get(path);
              if (Files.exists(Paths.get(path))) {
                  //Jetty knows how to find files on the file system
                  log.debug("Located {} '{}' on file system", name, path);
                  return path;
              } else {
                  //Maybe it's a resource on the Classpath. Jetty needs that converted to a URL.
                  //(e.g. "jar:file:/path/to/my.jar!<path>")
                  URL url = JettyServer.class.getResource(path);
                  if (url != null) {
                      log.debug("Located {} '{}' on Classpath", name, path);
                      return url.toExternalForm();
                  } else {
                      throw new IllegalArgumentException(String.format("%s '%s' not found", name, path));
                  }
              }
          }
      }
docs: Jetty treats non-URL paths are file paths interpreted in the current working directory.
  Provide ability to accept paths to resources on the Classpath.
  @param path
  @param name Descriptive name of what  is for. Used in logs, error messages
  @return Path in a format Jetty will understand, even if it is a Classpath-relative path.