}
    }
    return true;
  }

  /** An implementation of {@link Collection#toString()}. */
  static String toStringImpl(Collection<?> collection) {
    StringBuilder sb = newStringBuilderForCollection(collection.size()).append('[');
    boolean first = true;
    for (Object o : collection) {
      if (!first) {
        sb.append(", ");
      }
      first = false;
      if (o == collection) {