Description
After upgrade to 5.3 I have soo many PhpStan issues like

Parameter #1 $customerId of method Shopware\Administration\Controller\AdministrationController::isEmailValid() expects string, bool|float|int|string|null given.      

The ParameterBag has already methods like getBoolean / getInt. But not a getString. This would help to fix those issues really fast.

Example

$email = $request->request->getString('email');