if (MIN_SURROGATE <= c && c <= MAX_SURROGATE) {
          // Check that we have a well-formed surrogate pair.
          if (Character.codePointAt(sequence, i) == c) {
            throw new IllegalArgumentException(unpairedSurrogateMsg(i));
          }
          i++;
        }
      }
    }
    return utf8Length;
  }

  /**
   * Returns {@code true} if {@code bytes} is a <i>well-formed</i> UTF-8 byte sequence according to