The notifications did not work for me because of
org.acegisecurity.AccessDeniedException: Invalid token provided.
Instead
http://{JENKINS_URL}/buildByToken/build?job={SOME+JOB+NAME}&token={TOKEN}/
use
http://{JENKINS_URL}/buildByToken/build?token={TOKEN}&job={SOME+JOB+NAME}/
Fixed! Bitbucket can now trigger jenkins build!