remote calendar: authenticate to ms graph api

src/Bundle/ChillCalendarBundle/DependencyInjection/Configuration.php

@@ -26,9 +26,20 @@ class Configuration implements ConfigurationInterface
         $treeBuilder = new TreeBuilder('chill_calendar');
         $rootNode = $treeBuilder->getRootNode('chill_calendar');
 
-        // Here you should define the parameters that are allowed to
-        // configure your bundle. See the documentation linked above for
-        // more information on that topic.
+        $rootNode->children()
+            ->arrayNode('remote_calendars_sync')->canBeEnabled()
+            ->children()
+            ->arrayNode('microsoft_graph')->canBeEnabled()
+            ->children()
+            ->scalarNode('machine_access_token')
+            ->isRequired()
+            ->info('Access token for writing to remote calendars')
+            ->end() // end of machine_access_token
+            ->end() // end of microsoft_graph children
+            ->end() // end of array microsoft_graph
+            ->end() // end of children's remote_calendars_sync
+            ->end() // end of array remote_calendars_sync
+            ->end();
 
         return $treeBuilder;
     }