Use data returned from authorization custom provider

[xinyao27]

I have a custom provider in next-auth (dingtalk).
The user already is being sent to the authorization URL and can autherize the application there.
Dingtalk then sends the user back to the callback URL (in this case localhost:3000/api/auth/callback/dingtalk?authCode=xxxxxxxxxx) with a authCode in the query.
How can I access this authCode in the query?

{
      id: 'dingtalk',
      name: '钉钉',
      type: 'oauth',
      clientId: config.oauth.dingtalk.clientId,
      clientSecret: config.oauth.dingtalk.clientSecret,
      authorization: {
        url: 'https://login.dingtalk.com/oauth2/auth',
        params: {
          redirect_uri: `${config.http.url}/api/auth/callback/dingtalk`,
          client_id: config.oauth.dingtalk.clientId,
          response_type: 'code',
          scope: 'openid',
          prompt: 'consent',
        },
      },
      token: {
        url: 'https://api.dingtalk.com/v1.0/oauth2/userAccessToken',
        async request(context) {
          console.log(context) // I thougt that the authCode maybe could be in the context here. Couldnt find it.

          const request = await fetch('https://api.dingtalk.com/v1.0/oauth2/userAccessToken', {
            method: 'POST',
            headers: {
              'x-acs-dingtalk-access-token': 'BE3xxxx',
              'Content-Type': 'application/json',
            },
            body: JSON.stringify({
              clientId: context.provider.clientId,
              clientSecret: context.provider.clientSecret,
              grantType: 'authorization_code',
              code: ??? // i need to get `authCode` from authorization and use it here
            }),
          })
          const data = await request.json()
          console.log(data)

          return { tokens: data.accessToken }
        },
      },
    }