private function setDateContext(\DateTime $dateContext = null)
    {
        if (!$dateContext) { // we havent set context so we need the default to be: now minus 15 mins, rounded to 5 min increment.
            $now = new \DateTime();
            $now->sub(new \DateInterval('PT15M'));
            // round down to 5 minute increment
            $now->setTime($now->format('H'), floor($now->format('i') / 5) * 5, 0);
            $dateContext = $now;
        }
        $this->dateContext = $dateContext;
    }