code: public void setPathPrefix(String... components) {
      assert components.length > 0;
      for (String component : components) {
        assert !component.contains("/") && !component.contains("\\") :
          "Path components must not contain path separators: " + component;
      }
      pathPrefix = Path.Combine(components);
    }
docs: Configures the prefix prepended to asset paths before fetching them from the app directory.
  Note that you specify path components as an array, <em>not</em> a single string that contains
  multiple components with embedded path separators.