Comment 1 for bug 1638622

It's possible, it's just done using the snapcraft core options `organize` and `snap` instead of options specific to the plugin (which is why copy was deprecated in favor of dump). For example:

    assets:
        source: git://github.com/ubuntu-core/identity-vault
        plugin: dump
        organize:
          settings.yaml: data/settings.yaml
        snap:
          - data/settings.yaml