code: public static boolean containsIgnoreCase(String input, String substring) {
          return contains(input.toUpperCase(), substring.toUpperCase());
      }
docs: Tests if a string contains the specified substring in a case insensitive way.
  Equivalent to <code>fn:contains(fn:toUpperCase(string), fn:toUpperCase(substring))</code>.
  
  @param input     the input string on which the function is applied
  @param substring the substring tested for
  @return true if the character sequence represented by the substring
  exists in the string