code: public static String normaliseWhitespace(String string) {
          StringBuilder sb = StringUtil.borrowBuilder();
          appendNormalisedWhitespace(sb, string, false);
          return StringUtil.releaseBuilder(sb);
      }
docs: Normalise the whitespace within this string; multiple spaces collapse to a single, and all whitespace characters
  (e.g. newline, tab) convert to a simple space
  @param string content to normalise
  @return normalised string