I would also love to have it give better feedback on which properties are being applied, which defaults, and which properties are being discarded for example because of miss-spelling (see also HSEARCH-1869, HSEARCH-1413 and https://github.com/hibernate/hibernate-search/commit/4483598d0ee0b132f3f5a57b9cbc9ac119edec2c ).

The way we apply configuration setting to the IndexWriter though is to not set any explicit value unless the user did specify one. So to log all the defaults values being applied would need some care in that area, to read which defaults are being applied by Lucene (which doesn't always offer a getter).

Also while it would be nice to have all components feed such information back to a single structure, so that we could log for example a nice looking table, many components actually could start lazily so we might want to keep this need in mind during HSEARCH-1214.