Merge branch '4.4' into 5.1

* 4.4:
  [Sendgrid-Mailer] Fixed envelope recipients on sendgridApiTransport
  mark the AssertingContextualValidator class as internal
  Fix the parameter names in the SecurityFactoryInterface::create() method
  [Serializer][ClassDiscriminatorMapping] Fix getMappedObjectType() when a discriminator child extends another one
  make return type correct

Author: fabpot

Test/ConstraintValidatorTestCase.php

@@ -385,6 +385,9 @@ private function getViolation(): ConstraintViolation
     }
 }
 
+/**
+ * @internal
+ */
 class AssertingContextualValidator implements ContextualValidatorInterface
 {
     private $context;