Drupal 8 Entity Query Conditions

$query = \Drupal::entityQuery('node');
$query = \Drupal::service('entity.query');

// To get a list of published articles
$node_ids = $query->get('node') 
->condition('type', 'article') 
->condition('status', 1)
->execute();

// To find all users with the Administrator role.
$admin_user_ids = $query->get('user') 
->condition('roles', 'Administrator', 'CONTAINS') 
->execute();