*/
  public static <E> ImmutableMultiset<E> copyOf(Iterable<? extends E> elements) {
    if (elements instanceof ImmutableMultiset) {
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableMultiset<E> result = (ImmutableMultiset<E>) elements;
      if (!result.isPartialView()) {
        return result;
      }
    }
    ImmutableMultiset.Builder<E> builder =

   *
   * @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableMultiset<E> copyOf(Iterable<? extends E> elements) {
    if (elements instanceof ImmutableMultiset) {
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableMultiset<E> result = (ImmutableMultiset<E>) elements;
      if (!result.isPartialView()) {
        return result;
      }
    }

import org.jspecify.annotations.Nullable;

/**
 * Implementation of {@link ImmutableMultiset} with zero or more elements.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
final class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
  private static final ImmutableEntry<?>[] EMPTY_ARRAY = new ImmutableEntry<?>[0];

    assertThat(ImmutableMultiset.copyOf(c)).isSameInstanceAs(c);
  }

  public void testCopyOf_shortcut_immutableMultiset() {
    Collection<String> c = ImmutableMultiset.of("a", "b", "c");
    assertThat(ImmutableMultiset.copyOf(c)).isSameInstanceAs(c);
  }

  public void testBuilderAdd() {
    ImmutableMultiset<String> multiset =

  }

  /** All the ways to create an ImmutableMultiset. */
  enum ConstructionPathway implements Construction<Multiset<Object>> {
    COPY_OF_COLLECTION {
      @Override
      public ImmutableMultiset<Object> create(List<?> keys) {
        return ImmutableMultiset.copyOf(keys);
      }
    },
    COPY_OF_ITERATOR {
      @Override
      public ImmutableMultiset<Object> create(List<?> keys) {

    assertThat(ImmutableMultiset.copyOf(c)).isSameInstanceAs(c);
  }

  public void testCopyOf_shortcut_immutableMultiset() {
    Collection<String> c = ImmutableMultiset.of("a", "b", "c");
    assertThat(ImmutableMultiset.copyOf(c)).isSameInstanceAs(c);
  }

  public void testBuilderAdd() {
    ImmutableMultiset<String> multiset =

final class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
  static final ImmutableMultiset<Object> EMPTY =
      JdkBackedImmutableMultiset.create(ImmutableList.of());

  RegularImmutableMultiset() {}

  static <E> ImmutableMultiset<E> create(Collection<? extends Entry<? extends E>> entries) {
    if (entries.isEmpty()) {
      return ImmutableMultiset.of();
    } else {

      }
    };
  }

  private static <T> ImmutableMultiset<T> multiset(T value, int count) {
    return multiset(ImmutableMap.of(value, count));
  }

  private static <T> ImmutableMultiset<T> multiset(T value1, int count1, T value2, int count2) {
    return multiset(ImmutableMap.of(value1, count1, value2, count2));
  }

  private static <T> ImmutableMultiset<T> multiset(Map<T, Integer> counts) {

      }
    };
  }

  private static <T> ImmutableMultiset<T> multiset(T value, int count) {
    return multiset(ImmutableMap.of(value, count));
  }

  private static <T> ImmutableMultiset<T> multiset(T value1, int count1, T value2, int count2) {
    return multiset(ImmutableMap.of(value1, count1, value2, count2));
  }

  private static <T> ImmutableMultiset<T> multiset(Map<T, Integer> counts) {

import java.util.Map;
import org.jspecify.annotations.Nullable;

/**
 * An implementation of ImmutableMultiset backed by a JDK Map and a list of entries. Used to protect
 * against hash flooding attacks.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
final class JdkBackedImmutableMultiset<E> extends ImmutableMultiset<E> {
  private final Map<E, Integer> delegateMap;
  private final ImmutableList<Entry<E>> entries;