code: static boolean isEmptyWhitespace(@Nullable final String s) {
          if (s == null) {
              return true;
          }
          return CharMatcher.WHITESPACE.matchesAllOf(s);
      }
docs: Returns flag whose value indicates if the string is null, empty or
  only contains whitespace characters
  
  @param s a string
  @return true if the string is null, empty or only contains whitespace characters