private int publicSuffixIndex() {
    int publicSuffixIndexLocal = publicSuffixIndexCache;
    if (publicSuffixIndexLocal == SUFFIX_NOT_INITIALIZED) {
      publicSuffixIndexCache =
          publicSuffixIndexLocal = findSuffixOfType(Optional.<PublicSuffixType>absent());
    }
    return publicSuffixIndexLocal;
  }

  /**
   * The index in the {@link #parts()} list at which the registry suffix begins. For example, for