I bumped into this while updating my examples code. Will attach a patch which fixes this shortly.
DrillDownQuery not working with AssociateFacetFields?
Bulk close 4.7.1 issues
Commit 1578529 from Michael McCandless in branch 'dev/branches/lucene_solr_4_7'
[ https://svn.apache.org/r1578529 ]
LUCENE-5522: backport to 4.7.x
Reopen to backport to 4.7.x...
Committed to trunk and 4x.
Commit 1576797 from Shai Erera in branch 'dev/branches/branch_4x'
[ https://svn.apache.org/r1576797 ]
LUCENE-5522: FacetConfig doesn't add drill-down terms for facet associations
Commit 1576790 from Shai Erera in branch 'dev/trunk'
[ https://svn.apache.org/r1576790 ]
+1, thanks Shai!
Patch fixes FacetsConfig and adds tests to both demo and facet packages.