* which approach to use, <b>don't worry</b> too much about it; just pick something that seems
 * reasonable and it will be fine.
 *
 * <ul>
 *   <li>If checking whether the <i>caller</i> has violated your method or constructor's contract
 *       (such as by passing an invalid argument), use the utilities of the {@link Preconditions}
 *       class instead.

 * types, and also for interfaces and public classes that have public parameter-less constructors.
 * When the non-null default value for a particular parameter type cannot be provided by {@code
 * NullPointerTester}, the caller can provide a custom non-null default value for the parameter type
 * via {@link #setDefault}.
 *
 * @author Kevin Bourrillion
 * @since 10.0
 */
@GwtIncompatible
@J2ktIncompatible
@ElementTypesAreNonnullByDefault

     * newFuture is a future that completes after this and all prior tasks are done.
     * oldFuture is the previous task's newFuture.
     * outputFuture is the future we return to the caller, a nonCancellationPropagating taskFuture.
     *
     * newFuture is guaranteed to only complete once all tasks previously submitted to this instance

   *
   * <p>The returned array will be "safe" in that no references to it are maintained by this queue.
   * (In other words, this method must allocate a new array). The caller is thus free to modify the
   * returned array.
   *
   * <p>This method acts as bridge between array-based and collection-based APIs.
   *
   * @return an array containing all of the elements in this queue
   */

     * manifest entry is already in {@code scannedFiles}, either because it was scanned earlier, or
     * it was intentionally added to the set by the caller, it will not be scanned again.
     *
     * <p>Note that when you call {@code location.scanResources(scannedFiles)}, the location will
     * always be scanned even if {@code scannedFiles} already contains it.
     */

  }

  /** Returns the domain name, normalized to all lower case. */
  @Override
  public String toString() {
    return name;
  }

  /**
   * Equality testing is based on the text supplied by the caller, after normalization as described
   * in the class documentation. For example, a non-ASCII Unicode domain name and the Punycode
   * version of the same domain name would not be considered equal.
   */
  @Override

       * The given directory is a filesystem root. All zero of its ancestors exist. This doesn't
       * mean that the root itself exists -- consider x:\ on a Windows machine without such a drive
       * -- or even that the caller can create it, but this method makes no such guarantees even for
       * non-root files.
       */
      return;
    }
    parent.mkdirs();
    if (!parent.isDirectory()) {

    }
  }

  /**
   * Views the array as an immutable list. The array must have only {@code E} elements.
   *
   * <p>The array must be internally created.
   */
  @SuppressWarnings("unchecked") // caller is reponsible for getting this right
  static <E> ImmutableList<E> asImmutableList(Object[] elements) {
    return unsafeDelegateList((List) Arrays.asList(elements));
  }

   * advantages to having the type are the ability to use its constructor reference below and the
   * parallelism with the primitive version. In short, it makes its caller ({@code flatMap})
   * simpler.
   *
   * @param <InElementT> the element type of the input spliterator
   * @param <OutElementT> the element type of the output spliterators
   */

   * Optional.orElseGet}, except when {@code supplier} returns {@code null}. In this case this
   * method throws an exception, whereas the Java 8+ method returns the {@code null} to the caller.
   *
   * @throws NullPointerException if this optional's value is absent and the supplier returns {@code
   *     null}
   */
  public abstract T or(Supplier<? extends T> supplier);

  /**