docs: private static String escapeDoubleQuotes(String s, int beginIndex, int endIndex) {
  
          if (s == null || s.length() == 0 || s.indexOf('"') == -1) {
              return s;
          }
  
          StringBuilder b = new StringBuilder();
          for (int i = beginIndex; i < endIndex; i++) {
              char c = s.charAt(i);
              if (c == '\\' ) {
                  b.append(c);
                  //ignore the character after an escape, just append it
                  if (++i>=endIndex) throw UndertowMessages.MESSAGES.invalidEscapeCharacter();
                  b.append(s.charAt(i));
              } else if (c == '"')
                  b.append('\\').append('"');
              else
                  b.append(c);
          }
  
          return b.toString();
      }