bug #5673 Fix collectionField nested prototype name (ytilotti)

This PR was merged into the 4.x branch.

Discussion
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Fix collectionField nested prototype name

Fix the prototype names of collection nested. Fix issue #4710

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Commits
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7393353 fix(field): Collection nested prototype name

src/Field/Configurator/CollectionConfigurator.php

@@ -62,6 +62,7 @@ public function configure(FieldDto $field, EntityDto $entityDto, AdminContext $c
         $field->setFormTypeOptionIfNotSet('allow_delete', $field->getCustomOptions()->get(CollectionField::OPTION_ALLOW_DELETE));
         $field->setFormTypeOptionIfNotSet('by_reference', false);
         $field->setFormTypeOptionIfNotSet('delete_empty', true);
+        $field->setFormTypeOptionIfNotSet('prototype_name', '__'.$field->getProperty().'name__');
 
         // TODO: check why this label (hidden by default) is not working properly
         // (generated values are always the same for all elements)