public String toJson() {
   JsonObject details = new JsonObject();
   details.addProperty(FIELD_LEVEL, level.toString());
   JsonArray conditionResults = new JsonArray();
   for (EvaluatedCondition condition : this.conditions) {
     conditionResults.add(toJson(condition));
   }
   details.add("conditions", conditionResults);
   return details.toString();
 }