minor #20536 [OptionsResolver] Support union of types (VincentLanglet)

This PR was squashed before being merged into the 7.3 branch.

Discussion
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[OptionsResolver] Support union of types

Closes #20531

But I'm not sure it's expected to be documented this way...

Commits
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f8667f5 [OptionsResolver] Support union of types

components/options_resolver.rst

@@ -305,13 +305,20 @@ correctly. To validate the types of the options, call
 
             // specify multiple allowed types
             $resolver->setAllowedTypes('port', ['null', 'int']);
+            // which is similar to
+            $resolver->setAllowedTypes('port', 'int|null');
 
             // check all items in an array recursively for a type
             $resolver->setAllowedTypes('dates', 'DateTime[]');
             $resolver->setAllowedTypes('ports', 'int[]');
+            $resolver->setAllowedTypes('endpoints', '(int|string)[]');
         }
     }
 
+.. versionadded:: 7.3
+
+    Union of type, using the ``|`` syntax, was introduced in Symfony 7.3.
+
 You can pass any type for which an ``is_<type>()`` function is defined in PHP.
 You may also pass fully qualified class or interface names (which is checked
 using ``instanceof``). Additionally, you can validate all items in an array