java - How to identify and verifying tokenId from google API? -

i can't find solution think general issue...

i use google api login, , according this article can tokenid using method

private string gettokenid(googlesigninresult result) {     string tokenid = null;     googlesigninaccount googlesigninaccount = result.getsigninaccount();     if (googlesigninaccount != null) {         tokenid = googlesigninaccount.getidtoken();     }     return tokenid; } 

it standard method, why method retern token id contains 857 char of string? , can't verify standard link

https://www.googleapis.com/oauth2/v3/tokeninfo?access_token= <857 char>;  

and response

{ "error_description": "invalid value" } 

i sure if google provide method token id there have method verify it...

what doing wrong?