云对象获取post请求的body内容

客户端发送pos请求调用云对象中的方法，参数在body中，我在云对象的方法中应该怎么获取body中的参数呢，云对象的方法参数是 {} 的，如图

请求入参: {  
  "args": {  
    "path": "/hasRegistered",  
    "httpMethod": "POST",  
    "headers": {  
      "content-length": "37",  
      "cookie": "acw_tc=2760826a16632364542188021ed21df8e46a10142a9c01f57a58f81c78575a",  
      "x5-uuid": "d5870fd5d72c04e781d5a4214aa2c8ac",  
      "x-client-ip": "1.202.246.19",  
      "x-forwarded-for": "1.202.246.19, 39.96.130.106",  
      "accept": "*/*",  
      "x-unity-version": "2021.3.7f1c1",  
      "x-real-ip": "1.202.246.19",  
      "host": "52046be3-56b9-4b9f-b4fb-3d559c9620c3.bspapp.com",  
      "content-type": "application/x-www-form-urlencoded",  
      "x-forwarded-by": "172.20.1.138:80",  
      "accept-encoding": "deflate, gzip",  
      "user-agent": "UnityPlayer/2021.3.7f1c1 (UnityWebRequest/1.0, libcurl/7.80.0-DEV)"  
    },  
    "queryStringParameters": {},  
    "isBase64Encoded": false,  
    "body": "username=ffffffssssss"  
  },  
  "requestId": "ac14018a1663236581413198904"  
}  
[co_user/ac14018a1663236581413198904/73ms/DEBUG] {}