Samsung released the source code of the GT-I9100_HK Galaxy SII Jelly Bean update.
The Galaxy SII is based on Android 4.1 with the new TouchWiz interface.
Thanks to this release developers could make easier new DEV roms for the GT-I9100_HK Galaxy S II.
The Source code is based on the Firmware I9100ZSLS6
You can download the source codes here at opensource.samsung.com Gt-I9100_HK (Galaxy SII)