}

  @Override
  ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive) {
    return getSubSet(0, headIndex(toElement, inclusive));
  }

  int headIndex(E toElement, boolean inclusive) {
    int index = Collections.binarySearch(elements, checkNotNull(toElement), comparator());
    if (index >= 0) {
      return inclusive ? index + 1 : index;
    } else {

   * {@link IllegalArgumentException} if passed a {@code toElement} greater than an earlier {@code
   * toElement}. However, this method doesn't throw an exception in that situation, but instead
   * keeps the original {@code toElement}.
   */
  @Override
  public ImmutableSortedSet<E> headSet(E toElement) {
    return headSet(toElement, false);
  }

  /**
   * @since 12.0
   */
  @Override

        boolean fromInclusive,
        @ParametricNullness V toElement,
        boolean toInclusive) {
      return wrap(
          getSortedSetDelegate().subSet(fromElement, fromInclusive, toElement, toInclusive));
    }

    @Override
    public NavigableSet<V> headSet(@ParametricNullness V toElement, boolean inclusive) {
      return wrap(getSortedSetDelegate().headSet(toElement, inclusive));
    }

    @Override

    }

    @Override
    public String toString() {
      return standardToString();
    }

    @Override
    public SortedSet<T> subSet(T fromElement, T toElement) {
      return standardSubSet(fromElement, toElement);
    }

    @Override
    public @Nullable T lower(T e) {
      return standardLower(e);
    }

    @Override
    public @Nullable T floor(T e) {

        boolean fromInclusive,
        @ParametricNullness V toElement,
        boolean toInclusive) {
      return wrap(
          getSortedSetDelegate().subSet(fromElement, fromInclusive, toElement, toInclusive));
    }

    @Override
    public NavigableSet<V> headSet(@ParametricNullness V toElement, boolean inclusive) {
      return wrap(getSortedSetDelegate().headSet(toElement, inclusive));
    }

    @Override

    throw new NoSuchElementException();
  }

  @Override
  ContiguousSet<C> headSetImpl(C toElement, boolean inclusive) {
    return this;
  }

  @Override
  ContiguousSet<C> subSetImpl(
      C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
    return this;
  }

  @Override
  ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {

    }

    @Override
    public SortedSet<E> subSet(E fromElement, E toElement) {
      synchronized (mutex) {
        return sortedSet(delegate().subSet(fromElement, toElement), mutex);
      }
    }

    @Override
    public SortedSet<E> headSet(E toElement) {
      synchronized (mutex) {
        return sortedSet(delegate().headSet(toElement), mutex);
      }
    }

    @Override

    }

    @Override
    public SortedSet<E> subSet(E fromElement, E toElement) {
      synchronized (mutex) {
        return sortedSet(delegate().subSet(fromElement, toElement), mutex);
      }
    }

    @Override
    public SortedSet<E> headSet(E toElement) {
      synchronized (mutex) {
        return sortedSet(delegate().headSet(toElement), mutex);
      }
    }

    @Override

      BoundType fromBoundType,
      @ParametricNullness E toElement,
      BoundType toBoundType) {
    // These are checked elsewhere, but NullPointerTester wants them checked eagerly.
    checkNotNull(fromBoundType);
    checkNotNull(toBoundType);
    return tailMultiset(fromElement, fromBoundType).headMultiset(toElement, toBoundType);
  }

  abstract Iterator<Entry<E>> descendingEntryIterator();

    }

    @Override
    public String toString() {
      return standardToString();
    }

    @Override
    public SortedSet<T> subSet(T fromElement, T toElement) {
      return standardSubSet(fromElement, toElement);
    }
  }

  @AndroidIncompatible // test-suite builders
  public static Test suite() {
    TestSuite suite = new TestSuite();