Setting up default-jre-headless (2:1.11-72) ...
Setting up zabbix-java-gateway (1:5.0.6-2+focal) ...
Created symlink /etc/systemd/system/multi-user.target.wants/zabbix-java-gateway.service → /lib/systemd/system/zabbix-java-gateway.service.
Job for zabbix-java-gateway.service failed because the control process exited with error code.
See "systemctl status zabbix-java-gateway.service" and "journalctl -xe" for details.
invoke-rc.d: initscript zabbix-java-gateway, action "start" failed.
● zabbix-java-gateway.service - Zabbix Java Gateway
     Loaded: loaded (/lib/systemd/system/zabbix-java-gateway.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Wed 2020-12-09 22:58:46 UTC; 24ms ago
    Process: 16400 ExecStart=/usr/sbin/zabbix_java_gateway (code=exited, status=1/FAILURE)

Dec 09 22:58:46 ubuntu systemd[1]: Starting Zabbix Java Gateway...
Dec 09 22:58:46 ubuntu zabbix_java_gateway[16403]: /usr/sbin/zabbix_java_gateway: line 68: java: command not found
Dec 09 22:58:46 ubuntu zabbix_java_gateway[16400]: Zabbix Java Gateway did not start

Dec 09 22:58:46 ubuntu systemd[1]: zabbix-java-gateway.service: Control process exited, code=exited, status=1/FAILURE
Dec 09 22:58:46 ubuntu systemd[1]: zabbix-java-gateway.service: Failed with result 'exit-code'.
Dec 09 22:58:46 ubuntu systemd[1]: Failed to start Zabbix Java Gateway.
dpkg: error processing package zabbix-java-gateway (--configure):
 installed zabbix-java-gateway package post-installation script subprocess returned error exit status 1
Processing triggers for libc-bin (2.31-0ubuntu9.1) ...
Processing triggers for ufw (0.36-6) ...
Processing triggers for systemd (245.4-4ubuntu3.3) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for ca-certificates (20201027ubuntu0.20.04.1) ...
Updating certificates in /etc/ssl/certs...
0 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d...