kafka08 simple consumer firehose

I also changed druid-api package, added a method "public long getLastOffsetCommitTime(); " in "interface Firehose". The  way to call new commit method is hacked by using reflection,  quick and dirty way, need to refactor to add some method to interface. 
I think between step 2 and step 3 it is hard to guarantee they are either successful at the same time or failed in the same time. And still there needs a way to let step 2 inform step 3 it is successfully store offset file . 
Changing an interface is the least thing I want to do. If you don't want to change interface I can create a kafkasimplePlumber which is dedicated to kafkasimple Firehose. Do you think it is a good solution?