This is the current config of my Java commuter. I replaced the fork and folding handlebar stem with a fixed long fork, which shaved off 400g from the bike. There is an unwanted impact to the geometry of the bike since that fork is designed to replace a alloy fork (the Java has stock carbon), it lowers the bikes front 3cm. The overall ground clearance i compensated with 451 wheels, the riding position is more aggressive now - like a road race bike.
The outfit shown is my daily ride, MTB saddle, short bullbar and grippy pedals. The weight is 7.1kg, with my lightest parts it would be 6.8 with lots of improvability left - but i prefer speed over weight.
The fork i got from Aliexpress for thirtysomething USD - i dont recommend this, i had to work over the fork a lot to make it fit, it was'nt raw but almost.