assertTrue("An Object should be equal to itself.", collection.equals(collection));
  }

  // Comparisons to null *are* defined.
  @SuppressWarnings("UndefinedEquals")
  public void testEquals_null() {
    // noinspection ObjectEqualsNull
    assertFalse("An object should not be equal to null.", collection.equals(null));
  }

  // A collection should essentially never be equal to a non-collection.
  @SuppressWarnings("UndefinedEquals")

    new ForwardingWrapperTester()
        .testForwarding(
            Collection.class,
            new Function<Collection, Collection>() {
              @Override
              public Collection apply(Collection delegate) {
                return wrap(delegate);
              }
            });
  }

  private static <T> Collection<T> wrap(Collection<T> delegate) {
    return new ForwardingCollection<T>() {
      @Override

    }

    @Override
    public boolean containsAll(Collection<?> collection) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.containsAll(collection);
    }

    @Override
    public boolean addAll(Collection<? extends E> collection) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.addAll(collection);
    }

    @Override

    @Override
    @SuppressWarnings({"unchecked", "rawtypes"}) // needed for arrays
    public Entry<String, Collection<Integer>>[] createArray(int length) {
      return new Entry[length];
    }

    @Override
    public Iterable<Entry<String, Collection<Integer>>> order(
        List<Entry<String, Collection<Integer>>> insertionOrder) {
      return insertionOrder;
    }

    @Override

  public void testEntrySetEquals() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k1(), v0()), mapEntry(k0(), v3()));
    Set<Entry<K, Collection<V>>> expected = new HashSet<>();
    expected.add(mapEntry(k0(), (Collection<V>) newHashSet(v0(), v3())));
    expected.add(mapEntry(k1(), (Collection<V>) newHashSet(v0())));
    new EqualsTester().addEqualityGroup(expected, multimap().asMap().entrySet()).testEquals();
  }

      return standardRemove(object);
    }

    @Override
    public boolean removeAll(Collection<?> collection) {
      return standardRemoveAll(collection);
    }

    @Override
    public boolean retainAll(Collection<?> collection) {
      return standardRetainAll(collection);
    }

    @Override
    public int size() {
      return standardSize();
    }

    @Override

        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.add(e3()));
          iterator.next();
        });
  }

  /**
   * Returns the {@link Method} instance for {@link #testAdd_nullSupported()} so that tests of
   * {@link java.util.Collections#checkedCollection(java.util.Collection, Class)} can suppress it

        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.add(e3()));
          iterator.next();
        });
  }

  /**
   * Returns the {@link Method} instance for {@link #testAdd_nullSupported()} so that tests of
   * {@link java.util.Collections#checkedCollection(java.util.Collection, Class)} can suppress it

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.features.CollectionSize;
import java.util.Collection;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * The subject-generator interface accepted by Collection testers, for testing a Collection at one
 * particular {@link CollectionSize}.
 *
 * <p>This interface should not be implemented outside this package; {@link

import java.util.Collection;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
import org.jspecify.annotations.Nullable;

/**
 * A {@link BlockingQueue} which forwards all its method calls to another {@link BlockingQueue}.
 * Subclasses should override one or more methods to modify the behavior of the backing collection