Added patch based on trunk.
Added facet fields tests for integer and double types, and facet value stats is not available. Does it require new issue or reopen
Implementation of this issue can be improved in few cases:
1. Accumulate methods should not return stats specific numbers (it is generic). Attached solution with container class. Also made them private scoped.
Returning just missing fields from accumulate methods does not allow you to extend it with additional counts field, therefore i propose to leave void.
2. Reduced visibility of fields in FieldFacetStats.
Created getter to expose FieldFacetStats.facetStatsValues.
3. Methods FieldFacetStats#accumulateMissing and FieldFacetStats#accumulateTermNum does not throw any IO exception
4. We don't need intermediate maps to accumulate missing counts. Changed org.apache.solr.handler.component.FieldFacetStats#facetMissingNum
to work directly on StatsValues structure and removed org.apache.solr.handler.component.FieldFacetStats#accumulateMissing.
We don't need to have it in 2 phases.