This is not confirmed, but it might work.
Install MQTT Broker/Client adapter
Configure and start MQTT adapter
Add to /etc/wmbusmeters.conf
shell=/usr/bin/mosquitto_pub -h localhost -t wmbusmeters/$METER_ID -m "$METER_TOTAL_M3"
When wmbusmeters sends data, check under Objects -> mqtt.0/wmbusmeters/[meter_id] and you should see value reported