mailjet-8.x-2.7/modules/mailjet_subscription/src/Form/SubscriptionFormEditForm.php

<?php

namespace Drupal\mailjet_subscription\Form;

use Drupal\Core\Form\FormStateInterface;

/**
 *
 * Provides the add form for our Subscription Form.
 *
 * @ingroup mailjet_subscription
 */
class SubscriptionFormEditForm extends SubscriptionFormFormBase
{

    protected function actions(array $form, FormStateInterface $form_state)
    {
        $actions = parent::actions($form, $form_state);
        $actions['submit']['#value'] = $this->t('Save');
        return $actions;
    }

}