Review request [CALCITE-2404]

[Stamatis Zampetakis]

Hello,

Can somebody have a look at
[CALCITE-2404] Accessing structured-types is not implemented by the runtime
https://issues.apache.org/jira/browse/CALCITE-2404

The pull request is here:
https://github.com/apache/calcite/pull/762

Thanks,
Stamatis