minor #17183 [Validation] Add getGroupSequence return hint (mohamedGasmii)

This PR was merged into the 6.0 branch.

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[Validation] Add getGroupSequence return hint

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83a2d16 [Validation] Add getGroupSequence return hint

Author: xabbuh

validation/sequence_provider.rst

@@ -333,7 +333,7 @@ method, which should return an array of groups to use::
     {
         // ...
 
-        public function getGroupSequence()
+        public function getGroupSequence(): array|GroupSequence
         {
             // when returning a simple array, if there's a violation in any group
             // the rest of the groups are not validated. E.g. if 'User' fails,