How configure blackhole function in AppController?

Hello,

According to the documentation (https://book.cakephp.org/3.0/en/controllers/components/security.html#handling-blackhole-callbacks)

I try to do the blackhole function but i don’t understand what i should return.
(My final goal is to do a notification and redirect instead of the 4XX error page )

Exemple i have this form

<?= $this->Form->create($statutmembre, ['align' => $_horizontal_form['3-8-1']]) ?>
        <?= $this->Form->hidden('club_id', ['value'=>$_club_id]) ?>
        <?= $this->Form->input('statutmembres_type_id', ['label'=>'Type de statut','options' => $statutmembresTypes]) ?>
        <?= $this->Form->input('statut',['label' => __('Nom du statut')]); ?>
        <?= $this->MyHtml->submit('Enregistrer', 'floppy-o fa-lg', 'text-center','success') ?>
        <?= $this->Form->end() ?>
    <?= $this->MyHtml->end_box() ?>

The end of my function blackhole in appController

public function blackhole($type)
{
//…
return false;
}

My before filter is like the exemple in documentation

So when i modify the form with google code inspector for exemple.

If i change the hidden field, the save is still saved.
If i add a field, same thing.

It’s break security component in fact :confused:

When i tried to redirect in blackhole function, same thing, security component don’t do the job.

So my question, what i should do in this function to avoid save if the form is not correct ?
Did you have exemple for me ?

Thanks for advance