LUCENE-5902: Simplify the property handling by having a default; only add explicitclass include if actually given; refactor filterchain (TODO: maybe use a one-line groovy for this, we already have groovy loaded before running tests...?)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1622685 13f79535-47bb-0310-9956-ffa450edef68