SOLR-6476 refactored to get the Operation class outside

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1631397 13f79535-47bb-0310-9956-ffa450edef68
SOLR-5852: Add CloudSolrServer helper method to connect to a ZK ensemble

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1631409 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6476 change the error message

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1631420 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6485 added javadocs

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1631426 13f79535-47bb-0310-9956-ffa450edef68