Instanciate common attributes everywhere so one can simply use the extend method

logo.go

@@ -13,7 +13,10 @@ type Logo struct {
 
 // NewLogo creates a new Logo. It returns a *Logo.
 func NewLogo(uri string) *Logo {
-	return &Logo{URI: uri}
+	return &Logo{
+		CommonAttributes: newCommonAttributes(),
+		URI:              uri,
+	}
 }
 
 // Check checks the Logo for incompatibilities with RFC4287. It returns an