how to get source email details from google Calendar events source.url in JSON

Question

so i'm working on my project, getting events from Google Calendar and i want to show the content body from email source, here is the example one of my events list return.

{
   "kind": "calendar#event",
   "etag": "\"3408893757386000\"",
   "id": "_6tlnaqrle5p6cpb4dhmj4phpegsncq3aclhmcr3ie9nnarbe6cs6iqbbephj4dbc6kp3ie346lo68tb2cpmn0predkpmcpr4ehlmed9ocpgme",
   "status": "confirmed",
   "htmlLink": "https://www.google.com/calendar/event?eid=XzZ0bG5hcXJsZTVwNmNwYjRkaG1qNHBocGVnc25jcTNhY2xobWNyM2llOW5uYXJiZTZjczZpcWJiZXBoajRkYmM2a3AzaWUzNDZsbzY4dGIyY3BtbjBwcmVka3BtY3ByNGVobG1lZDlvY3BnbWUgYXBwcy5zYXNtaXRvYmFndXNzQG0",
   "created": "2024-01-05T09:27:58.000Z",
   "updated": "2024-01-05T09:27:58.693Z",
   "summary": "Stay at Hilton San Francisco Union Square",
   "description": "To see detailed information for automatically created events like this one, use the official Google Calendar app. https://g.co/calendar\n\nThis event was created from an email you received in Gmail. https://mail.google.com/mail?extsrc=cal&plid=ACUX6DNFxHlx_cWuOdV_6Fygl9Yq3JSChNeHvX0\n",
   "location": "Hilton San Francisco Union Square, San Francisco",
   "creator": {
    "email": "[email protected]",
    "self": true
   },
   "organizer": {
    "email": "[email protected]"
   },
   "start": {
    "date": "2027-04-11"
   },
   "end": {
    "date": "2027-04-14"
   },
   "transparency": "transparent",
   "visibility": "private",
   "iCalUID": "7kukuqrfedlm2f9t9vhjecflrroumn38iikvc25l5298d5pdubfmpgnm3fgdtkg58fag",
   "sequence": 0,
   "attendees": [
    {
     "email": "[email protected]",
     "self": true,
     "responseStatus": "accepted"
    }
   ],
   "guestsCanInviteOthers": false,
   "privateCopy": true,
   "reminders": {
    "useDefault": false
   },
   "source": {
    "url": "https://mail.google.com/mail?extsrc=cal&plid=ACUX6DNFxHlx_cWuOdV_6Fygl9Yq3JSChNeHvX0",
    "title": ""
   },
   "eventType": "default"
  }

i have tried to access link from source.url with accessToken but it just returned text/html, not the message id or anything that can lead me to email source details. or maybe anyone can show me the other way to get email body and events. * sorry for my bad english

i'm expecting to get both event details from google calendar and source email details that trigger events created from email markup hotel reservation in json.