Merge branch '6.4' into 7.2

* 6.4:
  Clarify the usage of the `value` variable in the When constraint documentation

Author: javiereguiluz

reference/constraints/When.rst

@@ -169,8 +169,9 @@ in your expression:
 ``this``
     The object being validated (e.g. an instance of Discount).
 ``value``
-    The value of the property being validated (only available when
-    the constraint is applied to a property).
+    Either the object being validated (when the constraint is applied to a class),
+    the value of the property being validated (when applied to a property),
+    or the :doc:`raw value </validation/raw_values>`.
 ``context``
     The :class:`Symfony\\Component\\Validator\\Context\\ExecutionContextInterface`
     object that provides information such as the currently validated class, the