Change record status: 
Project: 
Introduced in branch: 
8.8.x
Introduced in version: 
8.8.0
Description: 

Before

if (!empty($elements['#states'])) {
  drupal_process_states($elements);
}

After

use Drupal\Core\Form\FormHelper;

if (!empty($elements['#states'])) {
  FormHelper::processStates($elements);
}
Impacts: 
Module developers