* equals</i>. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero
 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting
 * collection will not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.

 * equals</i>. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero
 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting map will
 * not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *

    // protocol for completing a future is to assign the value field (which sets isDone to true) and
    // then to release waiters, followed by executing afterDone(), followed by releasing listeners.
    // That means that it is possible to observe that the future isDone and that your listeners
    // don't execute 'immediately'.  By checking isDone here we avoid that.

    }

    /**
     * Returns the option followed by a string representation of the given path elements.
     * For example, if this type is {@link #MODULES}, then the option is {@code "--module-path"}
     * followed by the specified path elements.
     *
     * @param paths the path to format as a tool option
     * @return the option associated to this path type followed by the given path elements,

 * equals</i>. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero
 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting
 * collection will not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.

      return fromMap.size();
    }

    @Override
    public boolean containsKey(@CheckForNull Object key) {
      return fromMap.containsKey(key);
    }

    // safe as long as the user followed the <b>Warning</b> in the javadoc
    @SuppressWarnings("unchecked")
    @Override
    @CheckForNull
    public V2 get(@CheckForNull Object key) {
      V1 value = fromMap.get(key);

     * on which it applies.
     *
     * @return the name of the tool option for this path type
     */
    @Nonnull
    Optional<String> option();

    /**
     * Returns the option followed by a string representation of the given path elements.
     * The path elements are separated by an option-specific or platform-specific separator.

  }

  /**
   * Combines four iterators into a single iterator. The returned iterator iterates across the
   * elements in {@code a}, followed by the elements in {@code b}, followed by the elements in
   * {@code c}, followed by the elements in {@code d}. The source iterators are not polled until
   * necessary.
   *

 * equals</i>. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero
 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting
 * collection will not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.

   * which it is unnecessary to programmatically distinguish between exception types or to extract
   * other information from the exception instance.
   *
   * <p>Exceptions from {@code Future.get} are treated as follows:
   *
   * <ul>
   *   <li>Any {@link ExecutionException} has its <i>cause</i> wrapped in an {@code X} if the cause
   *       is a checked exception, an {@link UncheckedExecutionException} if the cause is a {@code