我如何从Google获取访问令牌才能访问Voided Purchases API？

I'm trying to get the access token from Google to use the Voided Purchases API, to get the information about refunded orders on my app, but I couldn't find any tutorial from google guiding to get it through code.

Anyone could help me with that? I'm trying to do it using golang.

{
  "type": "service_account",
  "project_id": "api-####",
  "private_key_id": "#####",
  "private_key": "########",
  "client_email": "######",
  "client_id": "#####",
  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
  "token_uri": "https://oauth2.googleapis.com/token",
  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/quize-496%40api-7837675353051558736-36983.iam.gserviceaccount.com"
}