public void execute(int repNr) {
    StatelessKnowledgeSession ksession = kbase.newStatelessKnowledgeSession();
    Applicant applicant = new Applicant("Mr John Smith", 21, MALE);

    if (applicant.isValid()) throw new RuntimeException("Applicant shouldn't be valid");
    ksession.execute(applicant);
    if (!applicant.isValid()) throw new RuntimeException("Applicant should be valid");
  }