Method first

guava/src/com/google/common/collect/FluentIterable.java:512–516

Returns an {@link Optional} containing the first element in this fluent iterable. If the iterable is empty, {@code Optional.absent()} is returned. <p><b>{@code Stream} equivalent:</b> if the goal is to obtain any element, {@link Stream#findAny}; if it must specifically be the <i>first</i> element,

()

   *     iterator().next()} or {@link Iterables#getFirst} instead.
   */
  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
  public final Optional<@NonNull E> first() {
    Iterator<E> iterator = getDelegate().iterator();
    return iterator.hasNext() ? Optional.of(iterator.next()) : Optional.absent();
  }

  /**
   * Returns an {@link Optional} containing the last element in this fluent iterable. If the