Something of a long shot, but...
The admin utlity "admin search migrate" can be used to migrate a filesystem-stored document repository to the database. (refer to the Installation Guide).
I am trying to use it in a test instance at 13.0, and its failing with a NoClassDefFoundError - a bit of digging leads me to find "CLRT-71247 (S3) - Admin search migrate doesn’t work in 13.1 due to class file missing" (and the only reference to this bug is in the release notes for 13.3 as a patform defect - i.e. there is no associated KB article).
So my QUESTION is; is there a workaround I can use pre v13.3 to get this to work?