Liquibase's extension system scans the jar files for classes that could
be used by Liquibase. There is a list of packages to look in, however,
that should limit the search.
There was a fix in the upcoming 3.2.1 around fat jars that may
help. It should be out by the end of the week. If you are still having
errors, could you run with logLevel=debug and post the output?
Nathan