SOLR-6179: Better strategy for handling empty managed data to avoid spurious warning messages in the logs.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1607102 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5792: Simplified *AppendingBuffer APIs.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1607103 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6157: Refactor the ensureAllReplicasAreActive method into base class and ensure the ClusterState is updated to address intermittent test failures on Jenkins.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1607110 13f79535-47bb-0310-9956-ffa450edef68