The RangeFacetCounts implementations (LongRangeFacetCounts and DoubleRangeFacetCount) only work on single-valued fields today. In contrast, the more recently added LongValueFacetCounts implementation supports both single- and multi-valued fields (
LUCENE-7927). I'd like to extend multi-value support to both of the LongRangeFacetCounts implementations as well.
Looking through the implementations, I can't think of a good reason to not support this, but maybe I'm overlooking something?