Downgrade to Java 8…

GameScreen.java

@@ -46,7 +46,7 @@ class GameScreen
     public void draw(Turtle turtle, double elapsed)
     {
         TurtleWelt.globaleWelt.bildschirmEinfaerben(255, 255, 255);
-        for (var d : _drawables)
+        for (Drawable d : _drawables)
         {
             d.draw(turtle, elapsed);
         }