The default config should contain all the configuration options which are available in Sakai so this is a 2 part ticket.
Part one is to identify every configuration option which is known to the configuration service on startup. Ideally figuring out where each of the values were loaded from and whether they were overridden. (probably via temporary logging)
Part two is to insert them into the default configuration file with as much documentation as is known.
Part three is to correct any configuration options which do not have an appropriate default defined in the service where they are used.