传递默认的未定义值（swagger）节点js

Question

我想在参数中传递默认undefined值：

 "parameters": [
          {
            "in": "header",
            "name": "token",
            "description": "You should pass here token in a header ",
            "type": "string",
            "required": true
          },
          {
            "in": "path",
            "name": "contact_list_name",
            "description": "You should pass contact_list_name ",
            "default" : undefined,
            "type": "string"
          }
        ]

但是当我尝试传递它"default" : undefined,但是当我创建它时，我得到像'undefined' ..字符串类型的smth ..我怎么能像undefined那样sm或没有字符串的null型