The problem is all in the title. So here is my code (i cut some part to make it more visible) :

Constructor :

public function __construct() {   $user = DrupaluserEntityUser::load(Drupal::currentUser()->id());   $this->sub_forms['user'] = Drupal::service('entity.form_builder')->getForm($user); } 

buildForm :

public function buildForm(array $form, FormStateInterface $form_state) {   $sub_forms_keys = array_keys($this->sub_forms);   // INC ALL SUBFORM INTO THE MAIN FORM   foreach ($this->sub_forms as $key => $sub_form) {     // REMOVE THE PROCESS CALLBACK     if (!empty($sub_form['#process'])) {       unset($sub_form['#process']);     }      // ALTER THE SUBFORM     if ($key == $sub_forms_keys[0]) {       // user Alter       foreach ($sub_form as $field_key => $sub_form_field) {         // Pour tous les champs                         if (substr($field_key, 0, 10) != 'field_user') {           // Si ce n'est pas un champ personnalisé friterie           unset($sub_form[$field_key]); // Cacher le champ         }         else if (array_key_exists('widget', $sub_form[$field_key]))            // Si c'est un champ friterie et qu'il dispose d'un widget           $sub_form_field_widget = $sub_form[$field_key]['widget'][0];           $sub_form_field_widget['#states'] = array(             'visible' => array(               ':input[#edit-proprietaire-0]' => array('checked' => true),             )           );           dsm($sub_form_field_widget);         }       }     }      // ADD THE SUBFORM INTO THE MAIN FORM     $form[$key] = [       '#type' => 'container',       'form' => $sub_form     ];   }   return $form; } 

Here is a pastern link of a dsm() of a field to show you the structure and that the #states is include : http://pastebin.com/1a8AqVzm

Then here is the HTML code of the entity i want to focus (it’s a radio button) :

<input class="clear-panel-field panel-field-inline container-inline form-radio" data-drupal-selector="edit-proprietaire-0" type="radio" id="edit-proprietaire-0" name="proprietaire" value="0">