code: public static void printJsonString(Appendable out, CharSequence text)
          throws IOException
      {
          if (text == null)
          {
              out.append("null");
          }
          else
          {
              out.append('"');
              printCodePoints(out, text, EscapeMode.JSON);
              out.append('"');
          }
      }
docs: Prints characters as an ASCII-encoded JSON string, including surrounding
  double-quotes.
  If the {@code text} is null, this prints {@code null}.
  
  @param out the stream to receive the JSON data.
  @param text the text to print; may be {@code null}.
  
  @throws IOException if the {@link Appendable} throws an exception.
  @throws IllegalArgumentException
  if the text contains invalid UTF-16 surrogates.