What release of OUD are you currently using ?
In theory, migration was designed from ODSEE 11g. In the latest OUD release (11gR2Ps1), some tools like ds2oud are able to migrate from older DSEE versions, but I don't think this is the case for dps2oud.
If the conf.ldif file provided is valid, this looks like a bug to me. Feel free to open a Servvice Request to Oracle support.
PS: In which OUD deployment stage are you ? Is it proof of concept or do you plan to roll it out any time soon in prod ? In the later case only, feel free to drop me a mail directly at email@example.com if there are deployment details you would like to discuss.
This is planning for a real prod upgrade.
I tested dps2oud of recent OUD release, but still the same input, it says null while processing DS 7.0 dps config file.
I will try to contact you on the mentioned mail address.