Though it is not marked as required, Criterion a a part of Query object not being handled as optional, which makes some things awkward and inefficient.
For example to fetch a list of 10 last published Content now we have to use something like:
While it would be more efficient and natural to just have:
Both Legacy and Solr storage gateways need to be updated to handle this change.
We should also document in API Query class that $criterion property is optional and what it means if it is not provided.
Also, SPI SearchHandler::findContent() should document for implementers that null as criterion needs to be handled.