fix(auth): Use public refresh method for source credentials in ImpersonatedCredentials (googleapis#1884)

nbayati · web-flow · commit 8c0d91858a33 · 2025-12-09T12:34:43.000-08:00
This PR addresses a bug in ImpersonatedCredentials that causes a issues
when the source_credential is of a type that does not implement the
private _refresh_token method (for example, a custom credential type).
diff --git a/packages/google-auth/google/auth/impersonated_credentials.py b/packages/google-auth/google/auth/impersonated_credentials.py
@@ -286,7 +286,7 @@ def _refresh_token(self, request):
             self._source_credentials.token_state == credentials.TokenState.STALE
             or self._source_credentials.token_state == credentials.TokenState.INVALID
         ):
-            self._source_credentials._refresh_token(request)
+            self._source_credentials.refresh(request)
 
         body = {
             "delegates": self._delegates,
