Steps to reproduce:

• install Ubuntu 18.04.1 with Zabbix 4.0 repo
• install zabbix-java-gateway
• run zabbix_java_gateway -V/--version
• this version of Java will be installed by default as dependency:

  root@owbr:~# head -n 2 /etc/os-release 
  NAME="Ubuntu"
  VERSION="18.04.1 LTS (Bionic Beaver)"
  
  root@owbr:~# java -version
  openjdk version "1.8.0_181"
  OpenJDK Runtime Environment (build 1.8.0_181-8u181-b13-0ubuntu0.18.04.1-b13)
  OpenJDK 64-Bit Server VM (build 25.181-b13, mixed mode)
  

  root@owbr:~# apt show zabbix-java-gateway|grep Depend
  Depends: java6-runtime-headless | java7-runtime-headless | java8-runtime-headless, adduser, lsb-base
  

  root@owbr:~# apt install java8-runtime-headless
  Package java8-runtime-headless is a virtual package provided by:
    openjdk-8-jre-headless 8u181-b13-0ubuntu0.18.04.1
    openjdk-11-jre-headless 10.0.2+13-1ubuntu0.18.04.1
    default-jre-headless 2:1.10-63ubuntu1~02
  You should explicitly select one to install.
  

Result:

root@owbr:~# zabbix_java_gateway --version
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.UnsupportedClassVersionError: com/zabbix/gateway/JavaGateway has been compiled by a more recent version of the Java Runtime (class file version 54.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Expected:

• openjdk-11-jre-headless

  zabbix   21813  0.9  5.1 2517288 52124 ?       Sl   21:14   0:00 java -server -Dlogback.configurationFile=/etc/zabbix/zabbix_java_gateway_logback.xml -classpath lib:lib/android-json-4.3_r3.1.jar:lib/logback-classic-0.9.27.jar:lib/logback-core-0.9.27.jar:lib/slf4j-api-1.6.1.jar:bin/zabbix-java-gateway-4.0.0beta1.jar -Dzabbix.pidFile=/var/run/zabbix/zabbix_java_gateway.pid -Dsun.rmi.transport.tcp.responseTimeout=3000 com.zabbix.gateway.JavaGateway