Query.php

<?php

namespace Drupal\Core\Entity\Query\Null;

use Drupal\Core\Entity\Query\QueryAggregateInterface;
use Drupal\Core\Entity\Query\QueryBase;
use Drupal\Core\Entity\Query\QueryInterface;
use Drupal\Core\Entity\Query\Sql\ConditionAggregate;

/**
 * Defines the entity query for configuration entities.
 */
class Query extends QueryBase implements QueryInterface, QueryAggregateInterface {
  
  /**
   * {@inheritdoc}
   */
  public function execute() {
    if ($this->count) {
      return 0;
    }
    return [];
  }
  
  /**
   * {@inheritdoc}
   */
  public function existsAggregate($field, $function, $langcode = NULL) {
    return $this->conditionAggregate
      ->exists($field, $function, $langcode);
  }
  
  /**
   * {@inheritdoc}
   */
  public function notExistsAggregate($field, $function, $langcode = NULL) {
    return $this->conditionAggregate
      ->notExists($field, $function, $langcode);
  }
  
  /**
   * {@inheritdoc}
   */
  public function conditionAggregateGroupFactory($conjunction = 'AND') {
    return new ConditionAggregate($conjunction, $this);
  }

}