@SuppressWarnings({"unchecked", "nullness"})
  static int unsafeCompare(
      @Nullable Comparator<?> comparator, @Nullable Object o1, @Nullable Object o2) {
    if (comparator == null) {
      return ((Comparable<@Nullable Object>) o1).compareTo(o2);
    } else {
      return ((Comparator<@Nullable Object>) comparator).compare(o1, o2);
    }
  }

  /**

import java.io.Serializable;
import java.util.Comparator;
import org.jspecify.annotations.Nullable;

/** An ordering for a pre-existing comparator. */
@GwtCompatible
final class ComparatorOrdering<T extends @Nullable Object> extends Ordering<T>
    implements Serializable {
  final Comparator<T> comparator;

  ComparatorOrdering(Comparator<T> comparator) {
    this.comparator = checkNotNull(comparator);
  }

  @Override

  abstract SortedMultiset<E> forwardMultiset();

  @LazyInit private transient @Nullable Comparator<? super E> comparator;

  @Override
  public Comparator<? super E> comparator() {
    Comparator<? super E> result = comparator;
    if (result == null) {
      result = Ordering.from(forwardMultiset().comparator()).reverse();
      comparator = result;
    }
    return result;
  }

    assertEquals("a", elementSet.last());
    assertEquals(comparator, elementSet.comparator());
  }

  public void testNullAcceptingComparator() throws Exception {
    Comparator<@Nullable String> comparator = Ordering.<String>natural().<String>nullsFirst();
    TreeMultiset<@Nullable String> ms = TreeMultiset.create(comparator);

    ms.add("b");
    ms.add(null);
    ms.add("a");
    ms.add("b");

    Ordering<@Nullable Object> comparator = Ordering.allEqual();
    assertSame(comparator, comparator.reverse());

    assertEquals(0, comparator.compare(null, null));
    assertEquals(0, comparator.compare(new Object(), new Object()));
    assertEquals(0, comparator.compare("apples", "oranges"));
    assertSame(comparator, reserialize(comparator));
    assertEquals("Ordering.allEqual()", comparator.toString());

    Ordering<@Nullable Object> comparator = Ordering.allEqual();
    assertSame(comparator, comparator.reverse());

    assertEquals(0, comparator.compare(null, null));
    assertEquals(0, comparator.compare(new Object(), new Object()));
    assertEquals(0, comparator.compare("apples", "oranges"));
    assertSame(comparator, reserialize(comparator));
    assertEquals("Ordering.allEqual()", comparator.toString());

          Comparator<? super E> comparator,
          @ParametricNullness E key,
          List<? extends E> list,
          int foundIndex) {
        return FIRST_PRESENT.resultIndex(comparator, key, list, foundIndex) - 1;
      }
    };

    abstract <E extends @Nullable Object> int resultIndex(
        Comparator<? super E> comparator,
        @ParametricNullness E key,

     * @param comparator the comparator for ordering the elements in the priority queue
     * @return a new instance of {@link PriorityBlockingQueue}
     * @see PriorityBlockingQueue#PriorityBlockingQueue(int, Comparator)
     */
    public static <E> PriorityBlockingQueue<E> newPriorityBlockingQueue(final int initialCapacity, final Comparator<? super E> comparator) {

    final E lastInclusive;
    private final Comparator<? super E> comparator;
    private final TestSortedSetGenerator<E> delegate;

    public SortedSetSubsetTestSetGenerator(
        TestSortedSetGenerator<E> delegate, Bound to, Bound from) {
      this.to = to;
      this.from = from;
      this.delegate = delegate;

      SortedSet<E> emptySet = delegate.create();
      this.comparator = emptySet.comparator();

    }

    @Override
    public Iterator<E> iterator() {
      return Multisets.elementIterator(multiset().entrySet().iterator());
    }

    @Override
    public Comparator<? super E> comparator() {
      return multiset().comparator();
    }

    @Override
    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {