Reference:
Solr: https://solr.apache.org/guide/6_6/index.html
Solr schema with the dynamic field definitions (based on prefixes).
The default indexing descriptors used in Hyrax is defined in the link below
https://github.com/samvera/active_fedora/blob/511ee837cd9a461021e53d5e20f362b634de39a8/lib/active_fedora/indexing/default_descriptors.rb
A few additional descriptors in the basic metadata indexer
We use this knowledge to decide on how we want the value for a property to be treated in Solr