- fix variable name typo (LOGSTASH-1296)
- fix variable name typo (LOGSTASH-1296)

opentable/logstash-kafka,tinglinux/logstash-kafka,Aloomaio/logstash-kafka,Aloomaio/logstash-kafka,joekiller/logstash-kafka,tinglinux/logstash-kafka,opentable/logstash-kafka,joekiller/logstash-kafka