/**
* Connects another calendar to this calendar
*
* @param CalendarConnection $connection
* @return Calendar
* @throws InvalidEntityException
*/
public function addConnection(CalendarConnection $connection)
{
if ($connection->getCalendar() !== null) {
throw new InvalidEntityException("The already connected calendar cannot be re-connected.");
}
if ($connection->getConnectedCalendar() === null) {
throw new InvalidEntityException("The connected calendar must be specified.");
}
if (!$this->connections->contains($connection)) {
$connection->setCalendar($this);
$this->connections->add($connection);
}
return $this;
}
