private function recursiveScan($startFolder) {
		if (is_file($startFolder)) {
			$this->files[] = $startFolder;
			return;
		}
		$contents = scandir($startFolder);
		foreach ($contents as $content) {
			if (strpos($content, '.') === 0) {
				continue;
			}

			$path = $startFolder.DIRECTORY_SEPARATOR.$content;
			if (is_dir($path)) {
				$this->recursiveScan($path);
			} else {
				$fileExtension = pathinfo($content, PATHINFO_EXTENSION);
				if (strlen($fileExtension) == 0 || !in_array($fileExtension, $this->getFileExtensions())) {
					continue;
				}
				$this->files[] = $path;
			}
		}
	}