Fixes #176
Merge pull request #177 from kkasravi/issue_176

Fixes #176
Removed unused imports, minor cleanups
Merge pull request #179 from smarthi/suneel

Removed unused imports, minor cleanups
fix kafka key NPE and consumer close exception
Merge pull request #180 from manuzhang/fix_kafka_key_is_null

fix kafka key NPE and consumer close exception