field.setFieldValueExtractor not working in TreeGrid children items

[Hirn]

actually the question is in the title
This is how it is conceived and only the option using DataSource.transformResponse remains?

[Isomorphic]

DataSourceField.setFieldValueExtractor() is a DataSource-level API, therefore, it's either going to work for all components that access the DataSource, or for none - it can't fail specifically for TreeGrid child items.

You can start troubleshooting by looking at the data returned by the DataSource if you do a manual DataSource.fetchData().