After introducing own exp parser we broke usage of (not)in expression with an empty argument list, like in cayenneExp: {"exp":"id in $ids","params":{"ids":[]}}
Before it relied on Cayenne to optimize this to just false, now it fails with incorrect SQL generated: id in ()

There's a room for optimization on Cayenne side (see CAY-2860) but for now it should be fixed in Agrest.