code: public boolean containsResource (String path)
      {
          try {
              if (resolveJarFile()) {
                  return false;
              }
              return (_jarSource.getJarEntry(path) != null);
          } catch (IOException ioe) {
              return false;
          }
      }
docs: Returns true if this resource bundle contains the resource with the specified path. This
  avoids actually loading the resource, in the event that the caller only cares to know that
  the resource exists.