---

- name: restart zabbix-server
  service: name=zabbix-server state=restarted
  when: not zabbix_server_started.changed # Do not restart if the server has just started

- name: restart zabbix-java-gateway
  service:
    name: zabbix-java-gateway
    state: "{{ (zabbix_server_conf['StartJavaPollers'] is defined and zabbix_server_conf['StartJavaPollers'] > 0) | ternary('restarted','stopped') }}"
  tags: zabbix
...