Imports cloud.google.com/go/iam/credentials/apiv1 cloud.google.com/go/storage golang.org/x/xerrors google.golang.org/api/iam/v1 google.golang.org/genproto/googleapis/iam/credentials/v1 Standard library imports context encoding/base64 encoding/json errors fmt io io/ioutil net/http net/url strconv strings time