MOSCOW (Reuters) – Eastbound natural gas flows through Russia’s Yamal-Europe pipeline jumped four-fold on their way to Poland on Friday, data from German network operator Gascade showed, amid a Russian attack on Ukraine. It was not immediately clear whether the higher flows were related to the developments in Ukraine, another major route for Russian gas exports to Europe. Russian state gas company Gazprom said on Thursday its gas exports to Europe via Ukraine was not affected. The pipeline between Poland and Germany usually accounts for about 15% of Russia’s westbound supply of gas to Europe a…