code: public static String unescapeJava(String str) {
          if (str == null) {
              return null;
          }
          try {
              StringWriter writer = new StringWriter(str.length());
              unescapeJava(writer, str);
              return writer.toString();
          } catch (IOException ioe) {
              // this should never ever happen while writing to a StringWriter
              ioe.printStackTrace();
              return null;
          }
      }
docs: <p>
  Unescapes any Java literals found in the <code>String</code>. For example, it will turn a sequence of
  <code>'\'</code> and <code>'n'</code> into a newline character, unless the <code>'\'</code> is preceded by
  another <code>'\'</code>.
  </p>
  
  @param str the <code>String</code> to unescape, may be null
  @return a new unescaped <code>String</code>, <code>null</code> if null string input