When we try to define a property with a "half_float" type, for example, it is silently ignored.

This seems caused by the fact we attempt to parse user-provided JSON into a PropertyMapping object, which defines the "type" field as an instance of the org.hibernate.search.backend.elasticsearch.document.model.impl.esnative.DataType enum, which cannot represent the "half_float" value.

One question, though, is why in the world don't we get an exception somewhere...