Open Java SMB server implementation

Is there an open implementation of a SMB/CIFS server in Java? The only implementation I can find at all is Alfresco's but it isn't open source.

A related question: assuming there is no such implementation, I'm surprised there isn't a library providing even a subset of SMB e.g. for simple file transfer. My intuition is that it wouldn't be massively difficult to implement a simple server (开发者_如何学Gobut of course would be very difficult to implement a complete solution like Samba). The fact that no one seems to have done it makes me suspicious that it is harder than I'd guess. Is there no implementation because it is difficult or because no one cares?

According to http://www.alfresco.com/media/releases/2007/10/jlan1007/ JLAN is available under the GPL from sourceforge.net/projects/alfresco/files/ -- scroll down to the JLAN section at the bottom.

Anyway looking at http://www.alfresco.com/products/aifs/ seem that they distribute it with dual licensing (no GPL mentioned) for developers and OEM...