entityTypeManager

$terms = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree('vocabulary_name', $parent_id, 1, TRUE);

Before:

$moderators = \Drupal::entityQuery('user')
 ->condition('status', 1)
 ->condition('roles', $moderator_role)
 ->execute();

After:

$nodes = $this->entityTypeManager->getStorage('node')->loadByProperties([
 'type' => 'product',
]);
foreach ($nodes as $node) {
 $node->delete();
}

$category_term = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadByProperties([
  'vid' => 'category',
  'field_category_id' => $id,
]);
$category_term = \reset($category_term);

/**
 * The entity type manager.
 *
 * @var \Drupal\Core\Entity\EntityTypeManagerInterface
 */
protected $entityTypeManager;
/**
 * The form constructor.
 *
 * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
 *   The entity type manager.
 */
public function