* Make URI Exctraction Namespace take more sane arguments
* Fixes https://github.com/druid-io/druid/issues/2669
* Update docs
* Rename error message
* Undo overzealous deletion of docs
* Explain caching mechanism a bit more in docs
* Move kafka-extraction-namespace to the Lookup framework.
* Address comments
* Fix missing kafka introspection
* Fix tests to be less racy
* Make testing a bit more leniant
* Make tests even more forgiving
* Add comments to kafka lookup cache method
* Move startStopLock to just use started
* Make start() and stop() idempotent
* Forgot to update test after last change, test now accounts for idempotency
* Add extra idempotency on stop check
* Add more descriptive docs of behavior
The reference to io.druid.extensions:kafka-extraction-namespace is wrong (should
be druid-kafka-extraction-namespace) and unnecessary (the extension id is written
at the top of the doc file).
Slim
David Lim
Gian Merlino
Charles Allen
Gaurav Kumar
Fangjin Yang