@CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testHashCode_containingNull() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    int expectedHashCode = 0;
    for (E element : elements) {
      expectedHashCode += (element == null) ? 0 : element.hashCode();
    }

    elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(

   * collection. If the specified collection is a {@link SortedSet} or a {@link PriorityQueue}, this
   * priority queue will be ordered according to the same ordering. Otherwise, this priority queue
   * will be ordered according to the {@linkplain Comparable natural ordering} of its elements.
   *
   * @param c the collection whose elements are to be placed into this priority queue

import java.util.Collection;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Creates collections, containing sample elements, to be tested.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public interface TestCollectionGenerator<E extends @Nullable Object>

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

    return MinimalCollection.of(e3(), e4());
  }

  protected int getNumEntries() {
    return getNumElements();
  }

  protected Collection<Entry<K, V>> getSampleEntries(int howMany) {
    return getSampleElements(howMany);
  }

  protected Collection<Entry<K, V>> getSampleEntries() {
    return getSampleElements();
  }

  @Override
  protected void expectMissing(Entry<K, V>... entries) {

    }

    protected TermsQueryBuilder regTermsQ(String name, Collection<?> values) {
        checkEsInvalidQueryCollection(name, values);
        TermsQueryBuilder termsQuery = QueryBuilders.termsQuery(name, values);
        regQ(termsQuery);
        return termsQuery;
    }

    protected IdsQueryBuilder regIdsQ(Collection<String> values) {
        checkEsInvalidQueryCollection("_id", values);

   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {
      @Override
      public Iterator<T> iterator() {
        return collection.iterator();
      }
    };
  }

  public void testEquals() {
    new EqualsTester()

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

  }

  @Override
  protected Collection<Method> suppressForConcurrentSkipListMap() {
    List<Method> methods = new ArrayList<>();
    methods.addAll(super.suppressForConcurrentSkipListMap());
    methods.add(getContainsEntryWithIncomparableKeyMethod());
    methods.add(getContainsEntryWithIncomparableValueMethod());
    return methods;
  }

  @Override
  protected Collection<Method> suppressForHashtable() {

  }

  private boolean runCollectionTests = true;

  /**
   * Specify whether to skip the general collection tests. Call this method when testing a
   * collection that's both a queue and a list, to avoid running the common collection tests twice.
   * By default, collection tests do run.
   */
  @CanIgnoreReturnValue
  public QueueTestSuiteBuilder<E> skipCollectionTests() {
    runCollectionTests = false;