JaninoRelMetadataProvider should cache null value to improve performance.
Resolved in release 1.14.0 (2017-10-01)
Thanks Julian Hyde!
Fixed in http://git-wip-us.apache.org/repos/asf/calcite/commit/eaa56413. Thanks for the PR, Ted Xu!
I agree, a test is hard in this case. We can skip. Reviewing and testing now.
It's a bit hard to create a unit test. Julian Hyde could you please have a look at my pull request?
Here https://github.com/apache/calcite/pull/507 is a rough showcase. I'll try if I can create a test.