/** Parses execution options from a json object. Unrecognized elements are ignored. */
 public static ExecutionOptions fromJson(ObjectNode node) {
   ExecutionOptions ret = new ExecutionOptions();
   JsonNode x = node.get("timeLimit");
   if (x != null) {
     ret.timeLimit = x.asLong();
   }
   x = node.get("asynchronous");
   if (x != null) {
     ret.asynchronous = x.asLong();
   }
   return ret;
 }