/**
   * Returns a representation of {@code a} as an instance of type {@code B}. If {@code a} cannot be
   * converted, an unchecked exception (such as {@link IllegalArgumentException}) should be thrown.
   *
   * @param a the instance to convert; will never be null
   * @return the converted instance; <b>must not</b> be null
   */
  @ForOverride
  protected abstract B doForward(A a);

  /**

              try {
                if (state() != State.STOPPING) {
                  // This means that the state has changed since we were scheduled. This implies
                  // that an execution of runOneIteration has thrown an exception and we have
                  // transitioned to a failed state, also this means that shutDown has already
                  // been called, so we do not want to call it again.
                  return;

		return nil, nil, errInvalidArgument
	}

	// prepare getElapsedTime() to calculate elapsed time since we started trying formatting disks.
	// All times are rounded to avoid showing milli, micro and nano seconds
	formatStartTime := time.Now().Round(time.Second)
	getElapsedTime := func() string {
		return time.Now().Round(time.Second).Sub(formatStartTime).String()
	}

	var (
		tries   int

   *
   * <p>The returned view supports all optional operations supported by this {@code RangeSet}, with
   * the caveat that an {@link IllegalArgumentException} is thrown on an attempt to {@linkplain
   * #add(Range) add} any range not {@linkplain Range#encloses(Range) enclosed} by {@code view}.
   */
  RangeSet<C> subRangeSet(Range<C> view);

  // Modification

  /**

              try {
                if (state() != State.STOPPING) {
                  // This means that the state has changed since we were scheduled. This implies
                  // that an execution of runOneIteration has thrown an exception and we have
                  // transitioned to a failed state, also this means that shutDown has already
                  // been called, so we do not want to call it again.
                  return;

                    wagon.removeTransferListener(sha1ChecksumObserver);
                }

                if (downloaded) {
                    // keep the checksum files from showing up on the download monitor...
                    if (downloadMonitor != null) {
                        wagon.removeTransferListener(downloadMonitor);
                    }

 *             are incremented, and the total loading time, in nanoseconds, is added to {@code
 *             totalLoadTime}.
 *         <li>When an exception is thrown while loading an entry, {@code missCount} and {@code
 *             loadExceptionCount} are incremented, and the total loading time, in nanoseconds, is
 *             added to {@code totalLoadTime}.

 *             are incremented, and the total loading time, in nanoseconds, is added to {@code
 *             totalLoadTime}.
 *         <li>When an exception is thrown while loading an entry, {@code missCount} and {@code
 *             loadExceptionCount} are incremented, and the total loading time, in nanoseconds, is
 *             added to {@code totalLoadTime}.

     * directory or a {@code pom.xml} file with the {@code root="true"} attribute.
     * If there's no such directory, an {@code IllegalStateException} will be thrown.
     *
     * @throws IllegalStateException if the root directory could not be found
     * @see #getTopDirectory()
     * @since 4.0.0
     */
    Path getRootDirectory();

    /**

   * function that also supports reverse conversion.
   *
   * <p>If you are okay with {@code null} being returned for an unrecognized key (instead of an
   * exception being thrown), you can use the method reference {@code map::get} instead. Note that
   * it is not serializable unless you explicitly make it {@link Serializable}, typically by writing
   * {@code (Function<K, V> & Serializable) map::get}.