pubsub: clarify that Topic is goroutine-safe
Fixes
@@ -44,6 +44,8 @@ const (
var ErrOversizedMessage = bundler.ErrOversizedItem
// Topic is a reference to a PubSub topic.
+//
+// The methods of Topic are safe for use by multiple goroutines.
type Topic struct {
s service
// The fully qualified identifier for the topic, in the format "projects/<projid>/topics/<name>"
