Spec mutate filter: using explicit result expectations
Spec mutate filter: using explicit result expectations

Should make the tests easier to reason about

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