TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);
CategoryPath tags = new CategoryPath("tags");
CategoryPath genre = new CategoryPath("genre");
FacetSearchParams fsp = new FacetSearchParams(new SumIntAssociationFacetRequest(tags, 10),
new SumFloatAssociationFacetRequest(genre, 10));
FacetsCollector fc = FacetsCollector.create(fsp, indexReader, taxoReader);
// MatchAllDocsQuery is for "browsing" (counts facets
// for all non-deleted docs in the index); normally
// you'd use a "normal" query, and use MultiCollector to