Isolation level

I am still looking for an solution for my lock level settings and therefore
I am digging through the OJB source.

What I am not sure at the moment is if the setting of the isolation-level is
generally ignored in OJB?
<descriptor-repository version="1.0" isolation-level="read-comitted">

I couldn't find the place in the OJB code where the isolation level is set
to the DescriptorRepository and later to the connection.
In my optionion the isolation-level in the XML file is ignored.

Could someone point me in the right direction?

Thanks in advance,
CL