URL: http://localhost:8080/odata4/olingo_basic/Source/SimpleTableView/?$filter=stringval%20eq%20null
Actual result: {"error":{"code": null,"message": "OData Library: An exception without message text was thrown."}}
Expected result: Return all entities where stringval equals null

See: http://docs.oasis-open.org/odata/odata/v4.0/errata02/os/complete/part1-protocol/odata-v4.0-errata02-os-part1-protocol-complete.html#_Toc406398303
http://docs.oasis-open.org/odata/odata/v4.0/errata02/os/complete/part2-url-conventions/odata-v4.0-errata02-os-part2-url-conventions-complete.html#_Toc406398155