/**
* Adds a subfolder to this folder.
* @param Folder $child The folder to add as subfolder.
* @throws FolderException Thrown if this folder is not the parent of the child folder (DNA-tested).
* @author Björn Hjortsten
* @return void
*/
protected function addChild(Folder $child)
{
if ($child->getParentId() == $this->getId()) {
$this->children[$child->getId()] = $child;
} else {
throw new FolderException(sprintf('The supplied folder is not a child of this folder. This folders id: %d, childs id: %d, childs parent id: %d', $this->getId(), $child->getId(), $child->getParentId()));
}
}
