fix compile error in KafkaToHdfs
fix compile error in KafkaToHdfs

SteamShon/incubator-s2graph,daewon/incubator-s2graph,jongwook/incubator-s2graph,SteamShon/incubator-s2graph,daewon/incubator-s2graph,SteamShon/incubator-s2graph,jongwook/incubator-s2graph