assertThat(SerializableTester.reserialize(ImmutableClassToInstanceMap.of()))
        .isSameInstanceAs(ImmutableClassToInstanceMap.of());
  }

  public void testCopyOf_map_empty() {
    Map<Class<?>, Object> in = emptyMap();
    ClassToInstanceMap<Object> map = ImmutableClassToInstanceMap.copyOf(in);
    assertTrue(map.isEmpty());
    assertThat(map).isSameInstanceAs(ImmutableClassToInstanceMap.of());

import java.io.Serializable;
import java.util.List;
import java.util.Map.Entry;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@link ImmutableClassToInstanceMap}.
 *
 * @author Kevin Bourrillion
 */
@NullUnmarked
final class ClassToInstanceMapTesting {
  abstract static class TestClassToInstanceMapGenerator
      implements TestMapGenerator<Class<?>, Impl> {

  // We would use ArbitraryInstances, but it returns 0, invalid for many RateLimiter methods.
  private static final ImmutableClassToInstanceMap<Object> PARAMETER_VALUES =
      ImmutableClassToInstanceMap.builder()
          .put(int.class, 1)
          .put(long.class, 1L)
          .put(double.class, 1.0)
          .put(TimeUnit.class, SECONDS)
          .build();

  // We would use ArbitraryInstances, but it returns 0, invalid for many RateLimiter methods.
  private static final ImmutableClassToInstanceMap<Object> PARAMETER_VALUES =
      ImmutableClassToInstanceMap.builder()
          .put(int.class, 1)
          .put(long.class, 1L)
          .put(double.class, 1.0)
          .put(TimeUnit.class, SECONDS)
          .build();

import java.util.Spliterator;
import org.jspecify.annotations.NonNull;
import org.jspecify.annotations.Nullable;

/**
 * A mutable class-to-instance map backed by an arbitrary user-provided map. See also {@link
 * ImmutableClassToInstanceMap}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap">{@code
 * ClassToInstanceMap}</a>.
 *
 * @author Kevin Bourrillion

import com.google.common.base.Ticker;
import com.google.common.collect.BiMap;
import com.google.common.collect.ClassToInstanceMap;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableClassToInstanceMap;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;

import com.google.common.base.Ticker;
import com.google.common.collect.BiMap;
import com.google.common.collect.ClassToInstanceMap;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableClassToInstanceMap;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;