* {@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

    }

    @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) {

   * {@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

      return new FilteredSortedSet<>(
          ((SortedSet<E>) unfiltered).subSet(fromElement, toElement), predicate);
    }

    @Override
    public SortedSet<E> headSet(@ParametricNullness E toElement) {
      return new FilteredSortedSet<>(((SortedSet<E>) unfiltered).headSet(toElement), predicate);
    }

    @Override

    }

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

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

  public static Test suite() {
    TestSuite suite = new TestSuite();

    suite.addTestSuite(ForwardingSortedSetTest.class);
    suite.addTest(

    }

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

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

  public static Test suite() {
    TestSuite suite = new TestSuite();

    suite.addTestSuite(ForwardingSortedSetTest.class);
    suite.addTest(

    @Override
    ImmutableSortedSet<C> headSetImpl(C toElement, boolean inclusive) {
      return subSet(Range.upTo(toElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    ImmutableSortedSet<C> subSetImpl(
        C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
      if (!fromInclusive && !toInclusive && Range.compareOrThrow(fromElement, toElement) == 0) {
        return ImmutableSortedSet.of();

      @Override
      public SortedSet<E> headSet(@ParametricNullness E toElement) {
        return removeOnlySortedSet(super.headSet(toElement));
      }

      @Override
      public SortedSet<E> subSet(
          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
        return removeOnlySortedSet(super.subSet(fromElement, toElement));
      }

      @Override

      @Override
      public SortedSet<E> headSet(@ParametricNullness E toElement) {
        return removeOnlySortedSet(super.headSet(toElement));
      }

      @Override
      public SortedSet<E> subSet(
          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
        return removeOnlySortedSet(super.subSet(fromElement, toElement));
      }

      @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