create voter which blocks deletion if a workflow exists

src/Bundle/ChillMainBundle/DependencyInjection/ChillMainExtension.php

@@ -256,6 +256,13 @@ class ChillMainExtension extends Extension implements
             'channels' => ['chill'],
         ]);
 
+        $container->prependExtensionConfig('security', [
+            'access_decision_manager' => [
+                'strategy' => 'unanimous',
+                'allow_if_all_abstain' => false,
+            ],
+        ]);
+
         //add crud api
         $this->prependCruds($container);
     }