code: @Override
      public Object parse(IGroup group, JsonRuleParser parser) {
          // rules
          BasicDBList operates = new BasicDBList();
          for (JsonRule jsonRule : group.getRules()) {
              operates.add(parser.parse(jsonRule));
          }
  
          // AND or OR
          BasicDBObject andOrObj = new BasicDBObject();
          andOrObj.append(EnumCondition.AND.equals(group.getCondition()) ? "$and" : "$or", operates);
  
          // Not
          if (group.getNot() != null && group.getNot()) {
              BasicDBList list = new BasicDBList();
              list.add(andOrObj);
              return new BasicDBObject("$nor", list);
          }
          return andOrObj;
      }
docs: 解析
  @param group
  @param parser
  @return