GUC custom variables broken - Mailing list pgsql-hackers

I have the following in my postgresql.conf

custom_variable_classes = 'pljava'
pljava.classpath = 
'C:\\Tada\\Workspace\\org.postgresql.pljava\\build\\pljava.jar'

It worked fine with 8.0.0beta2. The beta4 however, gives me the 
following message:
   FATAL:  unrecognized configuration parameter "pljava.classpath"

What happened?

Regards,
Thomas Hallgren