* @param start1
   * @param end1
   * @param string2
   * @param start2
   * @param end2
   * @return int
   */
  static int helpFindMatchingPrefixLength(String string1, int start1, int end1, String string2, int start2, int end2) {
    { int i1 = start1;
      int i2 = start2;

      while ((i1 < end1) &&
          ((i2 < end2) &&
           (string1.charAt(i1) == string2.charAt(i2)))) {
        i1 = i1 + 1;
        i2 = i2 + 1;
      }
      return (i1 - start1);
    }
  }