* of the supertype that suggests that implementations are expected to tolerate null. That said, I
   * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
   * someone still manages to pass null, let's continue to have the method work.
   *

import java.util.regex.MatchResult;
import java.util.regex.Pattern;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@link ArbitraryInstances}.
 *
 * @author Ben Yu
 */
@NullUnmarked
public class ArbitraryInstancesTest extends TestCase {

  public void testGet_primitives() {

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;
import org.jspecify.annotations.Nullable;

/**
 * Static utility methods pertaining to {@link Queue} and {@link Deque} instances. Also see this
 * class's counterparts {@link Lists}, {@link Sets}, and {@link Maps}.
 *
 * @author Kurt Alfred Kluever

import com.google.thirdparty.publicsuffix.PublicSuffixPatterns;
import com.google.thirdparty.publicsuffix.PublicSuffixType;
import java.util.List;
import org.jspecify.annotations.Nullable;

/**
 * An immutable well-formed internet domain name, such as {@code com} or {@code foo.co.uk}. Only
 * syntactic analysis is performed; no DNS lookups or other network interactions take place. Thus

  @SuppressWarnings("GoodTime") // should be a Duration
  long refreshNanos = UNSET_INT;

  @Nullable Equivalence<Object> keyEquivalence;
  @Nullable Equivalence<Object> valueEquivalence;

  @Nullable RemovalListener<? super K, ? super V> removalListener;
  @Nullable Ticker ticker;

  Supplier<? extends StatsCounter> statsCounterSupplier = NULL_STATS_COUNTER;

  private CacheBuilder() {}

  public void testToStringImplWithNullKeys() throws Exception {
    Map<@Nullable String, String> hashmap = new HashMap<>();
    hashmap.put("foo", "bar");
    hashmap.put(null, "baz");

    assertEquals(hashmap.toString(), Maps.toStringImpl(hashmap));
  }

  public void testToStringImplWithNullValues() throws Exception {
    Map<String, @Nullable String> hashmap = new HashMap<>();
    hashmap.put("foo", "bar");

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests com.google.common.base.Suppliers.
 *
 * @author Laurence Gonsalves
 * @author Harry Heymann
 */
@NullMarked
@GwtCompatible
public class SuppliersTest extends TestCase {

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests com.google.common.base.Suppliers.
 *
 * @author Laurence Gonsalves
 * @author Harry Heymann
 */
@NullMarked
@GwtCompatible
public class SuppliersTest extends TestCase {

import com.google.common.base.MoreObjects;
import java.io.Serializable;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Objects;
import org.jspecify.annotations.Nullable;

/**
 * An immutable value object capturing some basic statistics about a collection of paired double
 * values (e.g. points on a plane). Build instances with {@link PairedStatsAccumulator#snapshot}.
 *

      K key, int hash, V value, @Nullable ReferenceEntry<K, V> next) {
    DummyEntry<K, V> entry = DummyEntry.create(key, hash, next);
    DummyValueReference<K, V> valueRef = DummyValueReference.create(value);
    entry.setValueReference(valueRef);
    return entry;
  }

  static class DummyEntry<K, V> implements ReferenceEntry<K, V> {
    private @Nullable K key;
    private final int hash;