Disable indexing in Flowpack.ElasticSearch.ContentRepositoryAdaptor at nodetype level

Hi guys,
is there a way to set specific nodetypes (either Content and Document) to be skipped by nodeindex:build completely?

The use case is that I got several structural nodetypes (like containers or alike) that I’d like to be ignored by the indexer.

I tried something like the following in my NodeTypes.yaml, as I saw it in another post here around, but no luck:

'My.Package:ContentNode':
  search:
    fulltext:
      isRoot: FALSE
      enable: FALSE

Any ideas? Is it even possible?

Thanks,
Nicola