*
   * <p><b>Note:</b>If you only need to know whether two maps have the same mappings, call {@code
   * left.equals(right)} instead of this method.
   *
   * @param left the map to treat as the "left" map for purposes of comparison
   * @param right the map to treat as the "right" map for purposes of comparison
   * @return the difference between the two maps
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>

   *       {@link #withoutCloser(AsyncFunction)}
   * </ul>
   *
   * <p>Example usage:
   *
   * <pre>{@code
   * // Fall back to a secondary input stream in case of IOException.
   * ClosingFuture<InputStream> inputFuture =
   *     firstInputFuture.catchingAsync(
   *         IOException.class, (closer, x) -> secondaryInputStreamClosingFuture(), executor);
   * }