add completely missing trait in example
add completely missing trait in example

adamallo/beast-mcmc,adamallo/beast-mcmc,adamallo/beast-mcmc,4ment/beast-mcmc,beast-dev/beast-mcmc,4ment/beast-mcmc,beast-dev/beast-mcmc,4ment/beast-mcmc,adamallo/beast-mcmc,4ment/beast-mcmc,4ment/beast-mcmc,adamallo/beast-mcmc,4ment/beast-mcmc,beast-dev/beast-mcmc,beast-dev/beast-mcmc,beast-dev/beast-mcmc,adamallo/beast-mcmc,beast-dev/beast-mcmc