code: public static String toPlain(String input) {
          Matcher matcher = SPACE_PATTERN.matcher(input);
          if (matcher.find()) {
              return matcher.replaceAll("");
          } else {
              return input;
          }
      }
docs: Removes any spaces contained in the String thereby converting the input into a plain IBAN
  
  @param input
  possibly pretty printed IBAN
  @return plain IBAN