openjdk version "1.8.0_111"
OpenJDK Runtime Environment (build 1.8.0_111-8u111-b14-2ubuntu0.16.04.2-b14)
OpenJDK Zero VM (build 25.111-b14, interpreted mode)
Hmm… Sorry, I thought that maybe you were using an older version of the JDK which does not support the ciphers used by the https://telegram.org/ site.
Not very helpful comment: notification works for me, I just sent a message to my mobile from the OpenHAB2 installation build number 597, so it is not something in the OH2 software itself