*
 * @author Louis Wasserman
 */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class JdkBackedImmutableSet<E> extends IndexedImmutableSet<E> {
  private final Set<?> delegate;
  private final ImmutableList<E> delegateList;

  JdkBackedImmutableSet(Set<?> delegate, ImmutableList<E> delegateList) {
    this.delegate = delegate;
    this.delegateList = delegateList;
  }

  @Override

           * populated.
           */
          return of(requireNonNull(dedupedElements[0]));
        default:
          return new JdkBackedImmutableSet<>(
              delegate, ImmutableList.asImmutableList(dedupedElements, distinct));
      }
    }
  }

  private static int estimatedSizeForUnknownDuplication(int inputElementsIncludingAnyDuplicates) {