Hey @jcalvocab,
looks like your server does not bring along the necessary dependencies yet (in this case, JAX-RS if I am not mistaken).
Please have a look at our installation guide for JBoss EAP 6 and follow it closely to get a working setup:
https://docs.camunda.org/manual/7.14/installation/full/jboss/manual/#required-setup-for-jboss-eap-6
Best
Tobias