SOLR-6770 Add/edit param sets and use them in requests

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1647748 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-6129: Assert that enums and dv are not leaked across threads.


git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1647750 13f79535-47bb-0310-9956-ffa450edef68