Implements \Drupal\Core\Entity\Query\QueryAggregateInterface::conditionAggregate().
public function conditionAggregate($field, $function = NULL, $value = NULL, $operator = '=', $langcode = NULL) {
$this
->aggregate($field, $function, $langcode);
$this->conditionAggregate
->condition($field, $function, $value, $operator, $langcode);
return $this;
}