minor #17909 [Validator] Add a few missing option default values (alexandre-daubois)

This PR was merged into the 5.4 branch.

Discussion
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[Validator] Add a few missing option default values

Commits
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107be53 [Validator] Add a few missing option default values

Author: javiereguiluz

reference/constraints/UniqueEntity.rst

@@ -145,7 +145,7 @@ Options
 em
 ~~
 
-**type**: ``string``
+**type**: ``string`` **default**: ``null``
 
 The name of the entity manager to use for making the query to determine
 the uniqueness. If it's left blank, the correct entity manager will be
@@ -155,7 +155,7 @@ not need to be used.
 ``entityClass``
 ~~~~~~~~~~~~~~~
 
-**type**: ``string``
+**type**: ``string`` **default**: ``null``
 
 By default, the query performed to ensure the uniqueness uses the repository of
 the current class instance. However, in some cases, such as when using Doctrine

reference/constraints/_comparison-propertypath-option.rst.inc

@@ -1,7 +1,7 @@
 ``propertyPath``
 ~~~~~~~~~~~~~~~~
 
-**type**: ``string``
+**type**: ``string`` **default**: ``null``
 
 It defines the object property whose value is used to make the comparison.
 

reference/constraints/_groups-option.rst.inc

@@ -1,7 +1,7 @@
 ``groups``
 ~~~~~~~~~~
 
-**type**: ``array`` | ``string``
+**type**: ``array`` | ``string`` **default**: ``null``
 
 It defines the validation group or groups of this constraint. Read more
 about :doc:`validation groups </validation/groups>`.