code: @VisibleForTesting
    static String icuEscape(String rawText) {
  
      Matcher matcher = ICU_SYNTAX_CHAR_NEEDING_ESCAPE_PATTERN.matcher(rawText);
      if (!matcher.find()) {
        return rawText;
      }
  
      StringBuffer escapedTextSb = new StringBuffer();
      do {
        String repl = ICU_SYNTAX_CHAR_ESCAPE_MAP.get(matcher.group());
        matcher.appendReplacement(escapedTextSb, repl);
      } while (matcher.find());
      matcher.appendTail(escapedTextSb);
      return escapedTextSb.toString();
    }
docs: Escapes ICU syntax characters in raw text.
  
  @param rawText The raw text to escaped.
  @return The escaped raw text. If the given raw text doesn't need escaping, then the same string
  object is returned.