Keywords in facet option are not complete

[emarzini]

The facet option returned with a empty search (without specify any kind of filter) are not complete.
We found this bug analyzing "Keywords" as an example.

If the user are searching for Document without filter we can see that some results have keyword that are not in the available option in the filter

If the user refines the search clicking on some filters, SOLR returns results and the available option for the facets. Now the user can see the keyword there weren't present before

The same behavior is present in the current production environment

[pbuttigieg]

To verify: Ensure that not only text literals are Retrieved, but also keywords in the DefinedTerm stanzas

@fils and @jmckenna to verify graph and SOLR congruence on our side

[pbuttigieg]

An example call made to Solr for the Documents Topic:

params={q=:&facet.field=type&facet.field=txt_keywords&facet.field=txt_contributor&facet.field=txt_provider&start=0&q.op=AND&sort=indexed_ts+desc&facet.mincount=1&fq=%2Btype:(CreativeWork)&rows=10&facet=true}