In lucene 4.1, only StandardFacetsAccumulator could be instantiated.
And as of lucene 4.2, it became possible to instantiate FacetsAccumulator.
I invoked FacetsCollector.getFacetResults twice, and I saw doubled facet counts.
If I invoke it three times, I see facet counts multiplied three times.
It all happens in FacetsAccumulator.accumulate.
StandardFacetsAccumulator doesn't have this bug since it frees facetArrays whenever StandardFacetsAccumulator.accumulate is called.
Is it a feature or a bug?