Don't treat empty string the same as nil when performing negate grep matching
Don't treat empty string the same as nil when performing negate grep matching

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