From 5f31cd7a34f275d5f9e30fd50a31a9bc5e5851cf Mon Sep 17 00:00:00 2001
From: Guillaume Blaquiere <guillaume.blaquiere@gmail.com>
Date: Wed, 15 Sep 2021 10:16:09 +0200
Subject: [PATCH] fix: add ImpersonationURL check

---
 google/google.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/google/google.go b/google/google.go
index 4d287ca..0594699 100644
--- a/google/google.go
+++ b/google/google.go
@@ -186,7 +186,7 @@ func (f *credentialsFile) tokenSource(ctx context.Context, params CredentialsPar
 		}
 		return cfg.TokenSource(ctx)
 	case impersonatedServiceAccount:
-		if f.SourceCredentials == nil {
+		if f.ServiceAccountImpersonationURL != "" && f.SourceCredentials == nil {
 			return nil, errors.New("missing 'source_credentials' field in credentials")
 		}