code: public boolean checkEndsWith(String str, String end) {
          int endLen = end.length();
          return str.regionMatches(!isSensitive, str.length() - endLen, end, 0, endLen);
      }
docs: Checks if one string ends with another using the case-sensitivity rule.
  <p>
  This method mimics {@link String#endsWith} but takes case-sensitivity
  into account.
  
  @param str  the string to check, not null
  @param end  the end to compare against, not null
  @return true if equal using the case rules
  @throws NullPointerException if either string is null