custom vars

Is there way to use custom vars like
```
custom:
dataSetBucket: 'images-roaddamage'
listBucket: 'dataset-list'
listKey: 'hk.json'
resultBucket: 'hk-result'
frontendBucket: 'hk-frontend'

```
?

The issue names no file, test, or entry point to inspect. Clarify whether the shown custom block should be accepted and how its values are consumed; completion would require an explicit supported behavior and a way to verify it.

Written by the indexing model from the issue text.