@CanIgnoreReturnValue
  @Override
  public @Nullable E poll() {
    final Monitor monitor = this.monitor;
    if (monitor.enterIf(notEmpty)) {
      try {
        return extract();
      } finally {
        monitor.leave();
      }
    } else {
      return null;
    }
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable E poll(long timeout, TimeUnit unit) throws InterruptedException {

package com.google.common.collect.testing;

import com.google.common.annotations.GwtCompatible;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * To be implemented by test generators of things that can contain elements. Such things include
 * both {@link Collection} and {@link Map}; since there isn't an established collective noun that

import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests for {@link ForwardingMultiset}.
 *
 * @author Hayward Chan
 * @author Louis Wasserman
 */
public class ForwardingMultisetTest extends TestCase {

import org.checkerframework.checker.nullness.qual.Nullable;
import org.junit.Ignore;

/**
 * Tester for {@link Multimap#put}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@ElementTypesAreNonnullByDefault
public class MultimapPutTester<K extends @Nullable Object, V extends @Nullable Object>

import org.checkerframework.checker.nullness.qual.Nullable;
import org.junit.Ignore;

/**
 * Tester for {@link Multimap#put}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@ElementTypesAreNonnullByDefault
public class MultimapPutTester<K extends @Nullable Object, V extends @Nullable Object>

 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface SortedSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends SetMultimap<K, V> {
  // Following Javadoc copied from Multimap.

  /**
   * Returns a collection view of all values associated with a key. If no mappings in the multimap

import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.RepositorySystemSession.CloseableSession;
import org.eclipse.aether.repository.WorkspaceReader;
import org.eclipse.sisu.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.helpers.MessageFormatter;

import static java.util.stream.Collectors.toSet;

/**
 */
@Named
@Singleton

        .testEquals();
  }

  public void testOfEntriesNull() {
    Entry<@Nullable Integer, @Nullable Integer> nullKey = entry(null, 23);
    assertThrows(
        NullPointerException.class,
        () -> ImmutableMap.ofEntries((Entry<Integer, Integer>) nullKey));
    Entry<@Nullable Integer, @Nullable Integer> nullValue = entry(23, null);
    assertThrows(
        NullPointerException.class,

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static convenience methods that serve the same purpose as Java language <a
 * href="https://docs.oracle.com/javase/8/docs/technotes/guides/language/assert.html">assertions</a>,

    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");
    ms.add(null, 2);