}

  /**
   * Provides a check of whether an exception type is valid for use with {@link
   * FuturesGetChecked#getChecked(Future, Class)}, possibly using caching.
   *
   * <p>Uses reflection to gracefully fall back to when certain implementations aren't available.
   */
  @VisibleForTesting
  static class GetCheckedTypeValidatorHolder {

    if (parameters.length != 1) {
      return false;
    }
    if (!parameters[0].equals(Object.class)) {
      return false;
    }
    return true;
  }

  /** Strategy for exception type matching used by {@link NullPointerTester}. */
  private enum ExceptionTypePolicy {

    /**
     * Exceptions should be {@link NullPointerException} or {@link UnsupportedOperationException}.
     */
    NPE_OR_UOE() {