Germany coach Julian Nagelsmann fully understands why teenage midfielder Paul Wanner, who is also eligible to play for Austria, has initially turned down an invitation to play for the German national team. Wanner, on loan at Heidenheim in the Bundesliga from Bayern Munich, has caught the eye so far this season and Nagelsmann was keen to take a look at him in Saturday’s Nations League game against Bosnia and Herzegovina in Freiburg and three days later in Hungary. However, with Nations League games counting as full internationals, appearing for Germany would have ruled Wanner out of playing for…