Since 1 August of 2016 if somebody want to connect openhab through myopenhab application must to upgrade Java 8 in the EmonPi Linux S.O.
The methodology to do that properly is described here:
If you connect it through DDNS everything will be ok even without this upgrade.
Thanks! Instructions to update have been added to OpenEnergyMonitor openhab readme.
Java 8 will be included in the next emonSD (pre-built SD card image) release.
echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu xenial main" | tee /etc/apt/sources.list.d/webupd8team-java.list
echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu xenial main" | tee -a /etc/apt/sources.list.d/webupd8team-java.list
apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys EEA14886
apt-get install oracle-java8-installer