protected function sendCacheControlHeader()
{
if ($this->sessionCacheLimiter !== null) {
if ($this->sessionCacheLimiter === '' && !headers_sent() && Yii::$app->getSession()->getIsActive()) {
header_remove('Expires');
header_remove('Cache-Control');
header_remove('Last-Modified');
header_remove('Pragma');
}
session_cache_limiter($this->sessionCacheLimiter);
}
$headers = Yii::$app->getResponse()->getHeaders();
if ($this->cacheControlHeader !== null) {
$headers->set('Cache-Control', $this->cacheControlHeader);
}
}