@Deprecated
    public Spider downloader(Downloader downloader) {
        return setDownloader(downloader);
    }
set the downloader of spider

@param downloader downloader
@return this
@see #setDownloader(us.codecraft.webmagic.downloader.Downloader)
@deprecated
webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java