Definitely agree with that. What got me wondering about the file separators was actually noticing that Liquibase normalised them to /, but at the point where the exception occurred, we seem to be passing the raw changeLogFile string.
Actually, looking at this a bit deeper, is there any reason that line 244 of DatabaseUpdater couldn’t just be replaced with:
DatabaseChangeLog changeLog = liquibase.getDatabaseChangeLog();
?