Why are you using root/root and 0755 for file permissions?
I've seen this when applying the config:
notice: /Stage[main]/Munin::Plugins::Base/File[/etc/munin/plugin-conf.d]/group: group changed 'munin' to 'root'
notice: /Stage[main]/Munin::Plugins::Base/File[/etc/munin/plugin-conf.d]/mode: mode changed '750' to '755'
750 appears to be more restrictive IMHO - e.g. for sensitive data in configs.