Support bounds changing after files got loaded.

src/Bundle/Resources/config/layers.yml

@@ -48,6 +48,8 @@ parameters:
     file:
       children: false
       icon: 'bundles/netzmachtcontaoleaflet/img/file.png'
+      boundsMode:
+        extend: true
 
 services:
   _defaults:

src/Bundle/Resources/contao/dca/tl_leaflet_layer.php

@@ -219,7 +219,7 @@ $GLOBALS['TL_DCA']['tl_leaflet_layer'] = [
         ],
 
         'file extends default' => [
-            '+config' => ['file'],
+            '+config' => ['file', 'boundsMode'],
             '+expert' => [
                 'onEachFeature',
                 'pointToLayer',