code: private boolean allIgnorable(String str) {
          // if the string is empty, we can just return true
          if (str == null || str.length() == 0) {
              return true;
          }
          RbnfLenientScanner scanner = formatter.getLenientScanner();
          return scanner != null && scanner.allIgnorable(str);
      }
docs: Checks to see whether a string consists entirely of ignorable
  characters.
  @param str The string to test.
  @return true if the string is empty of consists entirely of
  characters that the number formatter's collator says are
  ignorable at the primary-order level.  false otherwise.