SOLR-6365 refactoring and cleanup

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1622384 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6365 refactoring and cleanup

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1622385 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6024: Fix StatsComponent when using docValues=true multiValued=true (bug only on 4x trunk commit is just test changes demonstrating correct behavior)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1622386 13f79535-47bb-0310-9956-ffa450edef68