The XML-Namespaces used to build a content-package are hard-coded in XmlNamespace.java.
Currently the oak namespace is not supported. Therefor it's not possible to create a content-package to define an oak:index definition.
(please do not set issues with unmerged PRs to resolved)
the list of default list of namespaces is hardcoded, but the API of the content package builder allows to add your own ones. i assume you you are using this in context of CONGA, and in CONGA it's not yet possible to define additional XML namespaces for generated packages.
nevertheless it makes sense to add the oak NS to the list of default namespaces.
Sry, didn't know the workflow
Yes, the issue happens from conga
PR is merged