Rising isolationism and nationalism threaten the German tourism industry, two trade groups warned on Tuesday in a joint resolution calling for more hospitality. The statement follows a tragic knife attack, in Solingen, western Germany, allegedly by a 26-year-old Syrian man, which left three dead and eight injured during a city festival. The incident was swiftly accompanied by calls from opposition parties to halt immigration from Syria and Afghanistan. But in their resolution, German Tourism Association (DTV) and the German Travel Association (DRV), said only an open-minded Germany is an attra…