I haven't used dekorate (not a Java dev here), but afaict dekorate is run as part of the build process of the app and creates kubernetes yaml that can be used to deploy the app. Epinio expects the outcome of the build process to be a container image, not the helm chart itself (or resource yamls). I wonder if it would be possible to let
dekorate.io create those yamls in a pipeline somewhere (outside Epinio) and have that pipeline build a helm chart as well. That pipeline could then update the application helm chart epinio uses behind the scenes. It's hard to come up with a workflow without an actual example of an application though. I could be completely off with my suggestion.