Fields added with AddFields transformations in builder manifests are downcased

I have a transformation that adds a field. When I sync, the field does get added, but it is downcased. This does not happen on the airbyte test interface in-app.

```
transformations:
- type: AddFields
fields:
- path:
- conversationId
value: "{{stream_partition.conversationId}}"
```

The field is added, but it is added as `conversationid` instead of `conversationId`