Ref #44 - Now, the OLT field in NAP form is required.

src/FTTHBundle/Admin/NAPAdmin.php

@@ -74,8 +74,10 @@ class NAPAdmin extends BaseAdmin
             ])
             ->add('olt', null, [
                 'disabled' => $disabled,
+                'required' => true,
                 'attr' => [
                     'readonly' => $readonly,
+                    'required' => 'required'
                 ],
             ])
             ->add('slot', null, [