public function haveActivities(array $req_activities)
    {
        $activities = new ArrayCollection();

        foreach ($req_activities as $activity) {
            if ($activity = trim($activity) === '') {
                continue;
            }

            if ($activities->contains($activity)) {
                continue;
            }

            $activities->add($activity);
        }

        if (!$activities->isEmpty()) {
            $this->activities = $activities;
        }

        return $this;
    }