event listener - Expected type 'Symfony\Component\Form\FormInterface'. Found 'null' - Stack Overflow
Form] Using multiple Entity Form Types on the same underlying entity in one shared parent Form Type fires only one database request · Issue #6551 · symfony/symfony · GitHub
Wordpress Form Builder Plugin
Form Builder Interface - Docs
Remove any reference to not existing forms in FormBuilderInterface::submitForm() documentation [#1650198] | Drupal.org
A journey into Symfony form component - Speaker Deck
Symfony Forms - Use cases & optimization - Speaker Deck