FreeMarker

Consider running a project with the java "user.dir" property beeing
somewhere on "c:\" (not directly in the root).
There is no way of making the FileTemplateLoader accept loading files from
anywhere in c:\.
This is the reason: specifying the root for the FileTemplateLoader as "c:"
will resolve in fact to "user.dir" which may be any folder inside c.
Specifying the root as "c:\" will fail with a SecurityException because
when the FileTemplateLoader creates the canonicalPath, it automatically
appends File.separatorChar, therefore the root path will be "c:\\".
Consequently, any template on "c:" will fail to load with a
SecurityException saying that the specified template's path does not start
with "c:\\"...obviously it starts with just "c:\"