setImplementation(Executor.class, Dummies.DummyExecutor.class);
  }

  @SuppressWarnings("unchecked") // it's a subtype map
  private static <T> @Nullable Class<? extends T> getImplementation(Class<T> type) {
    return (Class<? extends T>) implementations.get(type);
  }

  private static final Logger logger = Logger.getLogger(ArbitraryInstances.class.getName());

  /**

            this.projectNames = projectSelectors;
        }
    }

    static class ExceptionThrown implements ExpectedResult {
        final Class<? extends Throwable> expected;
        final String partOfMessage;

        ExceptionThrown(final Class<? extends Throwable> expected, final String partOfMessage) {
            this.expected = expected;
            this.partOfMessage = partOfMessage;
        }
    }

        final V value = parent.remove(key);
        if (value != null) {
            return value;
        }
        return parent.remove(key);
    }

    @Override
    public void putAll(final Map<? extends K, ? extends V> m) {
        parent.putAll(m);
    }

    @Override
    public void clear() {
        parent.clear();
    }

    @Override
    public Set<K> keySet() {

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public abstract class AbstractMultimapTester<
        K extends @Nullable Object, V extends @Nullable Object, M extends Multimap<K, V>>
    extends AbstractContainerTester<M, Entry<K, V>> {

  private M multimap;

  protected M multimap() {
    return multimap;
  }

  /**

   */
  public interface FunctionWithIndex<T extends @Nullable Object, R extends @Nullable Object> {
    /** Applies this function to the given argument and its index within a stream. */
    @ParametricNullness
    R apply(@ParametricNullness T from, long index);
  }

  private abstract static class MapWithIndexSpliterator<
          F extends Spliterator<?>,
          R extends @Nullable Object,

    assertThat(onlyPresent).containsExactly("a", "c").inOrder();
  }

  public void testPresentInstances_wildcards() {
    List<Optional<? extends Number>> optionals =
        ImmutableList.<Optional<? extends Number>>of(Optional.<Double>absent(), Optional.of(2));
    Iterable<Number> onlyPresent = Optional.presentInstances(optionals);
    assertThat(onlyPresent).containsExactly(2);
  }

public class ConcurrentMapTestSuiteBuilder<K, V> extends MapTestSuiteBuilder<K, V> {
  public static <K, V> ConcurrentMapTestSuiteBuilder<K, V> using(TestMapGenerator<K, V> generator) {
    ConcurrentMapTestSuiteBuilder<K, V> result = new ConcurrentMapTestSuiteBuilder<>();
    result.usingGenerator(generator);
    return result;
  }

  @SuppressWarnings("rawtypes") // class literals
  static final List<? extends Class<? extends AbstractTester>> TESTERS =

public class ConcurrentMapTestSuiteBuilder<K, V> extends MapTestSuiteBuilder<K, V> {
  public static <K, V> ConcurrentMapTestSuiteBuilder<K, V> using(TestMapGenerator<K, V> generator) {
    ConcurrentMapTestSuiteBuilder<K, V> result = new ConcurrentMapTestSuiteBuilder<>();
    result.usingGenerator(generator);
    return result;
  }

  @SuppressWarnings("rawtypes") // class literals
  static final List<? extends Class<? extends AbstractTester>> TESTERS =

    @Override
    public void acceptPrimaryKeyMap(Entity entity, Map<String, ? extends Object> primaryKeyMap) {
    }

    @Override
    public void acceptAllColumnMap(Entity entity, Map<String, ? extends Object> allColumnMap) {
    }

    @Override
    public Map<String, Object> extractPrimaryKeyMap(Entity entity) {
        return null;
    }

      assertTrue(Thread.holdsLock(mutex));
      return delegate.put(rowKey, columnKey, value);
    }

    @Override
    public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.putAll(table);
    }

    @Override
    public @Nullable V remove(Object rowKey, Object columnKey) {