* created multimaps.
   *
   * @since 2.0
   */
  @DoNotMock
  public static class Builder<K, V> {
    @Nullable Map<K, ImmutableCollection.Builder<V>> builderMap;
    @Nullable Comparator<? super K> keyComparator;
    @Nullable Comparator<? super V> valueComparator;
    int expectedValuesPerKey = ImmutableCollection.Builder.DEFAULT_INITIAL_CAPACITY;

    /**

import java.util.NoSuchElementException;
import java.util.stream.Stream;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@code MoreCollectors}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@NullMarked
public class MoreCollectorsTest extends TestCase {
  public void testToOptionalEmpty() {

 * under the License.
 */
package org.apache.maven.api.services;

import java.nio.file.Path;

import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.Nullable;

/**
 * Represents a source for loading Maven Project Object Model (POM) files. This interface
 * extends the basic {@link Source} interface with specific functionality for handling

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import org.jspecify.annotations.Nullable;

/** Precondition checks useful in collection implementations. */
@GwtCompatible
final class CollectPreconditions {

  static void checkEntryNotNull(@Nullable Object key, @Nullable Object value) {
    if (key == null) {
      throw new NullPointerException("null key in entry: null=" + value);

  @Override
  public int size() {
    return getConnectingEdge() == null ? 0 : 1;
  }

  @Override
  public boolean contains(@Nullable Object edge) {
    E connectingEdge = getConnectingEdge();
    return connectingEdge != null && connectingEdge.equals(edge);
  }

  private @Nullable E getConnectingEdge() {
    return nodeToOutEdge.get(targetNode);
  }

    }
  }

  @Override
  public int indexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.indexOfImpl(this, object);
  }

  @Override
  public int lastIndexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
  }

  @Override
  public boolean contains(@Nullable Object object) {
    return indexOf(object) >= 0;
  }

    @SuppressWarnings("unused") // https://errorprone.info/bugpattern/FutureReturnValueIgnored
    Future<?> possiblyIgnoredError =
        threadPool.submit(
            new Callable<@Nullable Void>() {
              @Override
              public @Nullable Void call() throws InterruptedException {
                new Producer(q, 50).call();
                new Interrupter(mainThread).run();
                new Producer(q, 50).call();

    public CustomScheduler() {}

    /** A callable class that can reschedule itself using a {@link CustomScheduler}. */
    private final class ReschedulableCallable implements Callable<@Nullable Void> {

      /** The underlying task. */
      private final Runnable wrappedRunnable;

      /** The executor on which this Callable will be scheduled. */
      private final ScheduledExecutorService executor;

  public void testCopyOfNullKey() {
    ArrayListMultimap<@Nullable String, Integer> input = ArrayListMultimap.create();
    input.put(null, 1);
    assertThrows(
        NullPointerException.class,
        () -> ImmutableListMultimap.copyOf((ArrayListMultimap<String, Integer>) input));
  }

  public void testCopyOfNullValue() {
    ArrayListMultimap<String, @Nullable Integer> input = ArrayListMultimap.create();

  private static final class AlwaysEqual extends Ordering<@Nullable Object>
      implements Serializable {
    private static final AlwaysEqual INSTANCE = new AlwaysEqual();

    @Override
    @SuppressWarnings("UnusedVariable") // intentionally weird Comparator
    public int compare(@Nullable Object o1, @Nullable Object o2) {
      return 0;
    }

    @Override