Check out the following articles for more information:
- JMX monitoring: https://zabbix.com/documentation/current/manual/config/items/itemtypes/jmx_monitoring
- Java gateway: https://zabbix.com/documentation/4.0/manual/concepts/java
- Docs/howto/zabbix get jmx: https://www.zabbix.org/wiki/Docs/howto/zabbix_get_jmx
- Discovery of JMX objects: https://zabbix.com/documentation/4.0/manual/discovery/low_level_discovery/jmx