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

/** Never actually created; instead delegates to JdkBackedImmutableMultiset. */
final class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
  static final ImmutableMultiset<Object> EMPTY =
      JdkBackedImmutableMultiset.create(ImmutableList.of());

  RegularImmutableMultiset() {}

      return copyOf(contents);
    }

    @VisibleForTesting
    ImmutableMultiset<E> buildJdkBacked() {
      if (contents.isEmpty()) {
        return of();
      }
      return JdkBackedImmutableMultiset.create(contents.entrySet());
    }
  }

  static final class ElementSet<E> extends ImmutableSet.Indexed<E> {
    private final List<Entry<E>> entries;
    // TODO(cpovirk): @Weak?