docs: public URL resolveURL(FacesContext context, URL source, String path) throws IOException
      {
          if (path.startsWith("/"))
          {
              context.getAttributes().put(LAST_RESOURCE_RESOLVED, null);
              URL url = resolveURL(context, path);
              if (url == null)
              {
                  throw new FileNotFoundException(path + " Not Found in ExternalContext as a Resource");
              }
              return url;
          }
          else
          {
              return new URL(source, path);
          }
      }