Fragment deletion is not flagged anymore

[srascar]

Sonata packages

sonata-project/admin-bundle            3.88.0
sonata-project/article-bundle            1.5.0

Subject

The support for the _delete field has been lost when submitting the fragment form field

Steps to reproduce

• Create an ArticleAdmin
• Create a fragments field of type collection
• Edit the article to add a fragment
• Remove the fragment and submit the form
• Dump the value of _delete in pre_bind_data_callback
  ex:

$formMapper
            ->add('fragments', CollectionType::class, [
                'constraints'  => [new Valid()],
                'by_reference' => false,
                'label'        => false,
                'pre_bind_data_callback' => function ($value) {
                    dump($value);

                    // ...

Expected results

When the fragment has beed deleted, $value where the key id corresponds to the deleted fragment should contain a _delete key

Actual results

$value where the key id corresponds to the deleted fragment is never received

[VincentLanglet]

The support for the _delete field has been lost when submitting the fragment form field

Do you know in which version ?

[srascar]

It happened on tag 1.3
2a52eed#diff-ae864fbf4f9062ada8c1e8d888855a8f8b622efb0066e1ddcf7a0cf9d63b96e8L188

[VincentLanglet]

Do you know how to fix this ? Can you do the PR ? :)

[srascar]

Started #280