// work-around of a compiler type inference quirk that prevents the
    // following code from being compiled:
    // Comparator<Class<?>> comparator = null;
    // Map<Class<? extends Throwable>, String> map = newTreeMap(comparator);
    return new TreeMap<>(comparator);
  }

  /**
   * Creates an {@code EnumMap} instance.
   *
   * @param type the key type for this map