When a resource is added using KieHelper.addResource, any specified encoding is ignored when it is added to the MemoryFileSystem by KieFileSystemImpl.write(Resource) (effectively assuming the InputStream is already encoded in UTF-8).

Additionally, when the resource is read again by AbstractKieModule.getResource, it constructs a Resource object with no encoding specified, whereas it should probably specify an encoding of UTF-8, since it seems that sources are considered to be UTF-8 already at least in the case of the MemoryKieModule.

I've attached a fairly minimal test case where the rules bytes are passed in UTF-8 with the encoding explicitly specified. This currently produces an error when the default file encoding is not UTF-8 (eg, by passing -Dfile.encoding=latin1 as a JVM argument, or by using the default arguments on Windows).