Fix for several concurrency issues and optionally ignore duplicate metrics

Duplicate metrics should not lead to failure (#24)

Cherrypick e24d82e, a fix for KAFKA-7280; Synchronize consumer fetch request/response handling (#22)

Fix in parallel topic deletion and partition reassignment issue (#14)

cherry pick of fc5f6b0 to simplify timeout bookkeeping in the consume.

Adjust observer interface

This release contains 2 commits which together give observer more flexibility to handle produce request.

Add logging for unclean leader election and auto topic creation

This release contains two commits and one adds logging when unclean leader election happens and another one adds logging when auto topic creation happens.

Check callback null in addStopReplicaToBrokers and modify broker auditor interface

2.0.0.9

Adjust broker-side observer interface so that the interface only take…

[DO NOT USE] Disable snapshot file delete during topic deletion and group STOP_REPLICA messages during replica offline

Disable snapshot file delete during topic deletion and group STOP_REPLICA messages during replica offline

2.0.0.5

This release contains only one commit which adds an observer interface and a NoOpObserver implementation of the interface. This commit needs to be released so that kafka-server MP can use its artifacts to develop and test non-trivial observer implementations.

Cherry pick upstream fix for JBOD support

cherry-pick and back ported fixes for JBOD support:
KAFKA-8002; Log dir reassignment stalls if future replica has different segment base offset (apache#6346)

other commit since last release:
Set Bintray-related env variables via repository setting instead of in .travis.yml (#5)
KAFKA-7288; Fix check in SelectorTest to wait for no buffered bytes (apache#6415)

Cherry pick upstream patches

This release cherry-picks three upstream patches:

• KAFKA-7165: Retry the BrokerInfo registration into ZooKeeper (This is a workaround for ZOOKEEPER-2985)
• KAFKA-7288: Fix for SslSelectorTest.testCloseConnectionInClosingState
• KAFKA-7288 - Make sure no bytes buffered when relying on idle timeout in channel close test

2.0.0.2

KAFKA-8069: Setting expireTimestamp to None if it is the default valu…