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

inlineTextContent.go

@@ -15,7 +15,11 @@ type InlineTextContent struct {
 // newInlineTextContent creates a new InlineTextContent. It returns a
 // *InlineTextContent.
 func newInlineTextContent(mediaType, text string) *InlineTextContent {
-	return &InlineTextContent{Type: mediaType, Text: text}
+	return &InlineTextContent{
+		CommonAttributes: newCommonAttributes(),
+		Type:             mediaType,
+		Text:             text,
+	}
 }
 
 // isContent checks whether the InlineTextContent is a Content. It returns a