Different services, or the same one at different times, may have different default FS, so it doesn't make sense to persist a non-qualified path.
The logic to detect whether we are using default FS or not is anyway rather questionable e.g. it will run if the setting is set to the same value as the default fs, as long as it's set.
In fact might be more expensive that just making the path qualified as it iterates thru all the properties, including the ones added from getConfVarInputStream.
Bug
Major