I pushed it ‘as-is’ to GitHub - martingruening/openems-openhab: OpenEMS - Open Source Energy Management System
The code is in io.openems.edge.meter.sma.shm20
Edit: I don’t know what exactly happened. Today the code worked 
[modbus0 ] INFO [dbus.api.task.AbstractReadTask] [modbus0] FC3ReadHoldingRegisters [3:30865/0x7891]: 0000 0347
[re.Cycle] INFO [e.controller.debuglog.DebugLog] [ctrlDebugLog0] _sum[State:Ok Grid:839 W Consumption:839 W] meter0[L:839 W]
A manual ‘gradlew clean’ removed the problems which seem to be caused by a rookie software engineer in front of the keyboard 
Can you please advise on the topic ‘Symmetic vs. Asymmetric’ meter and how to convert Modbus registers available to channels using logic mentioned above?