It is not possible to start EAP with only Oracle JDK 11 installed

Since EAP7.0 RPMs there is hard-coded JAVA_HOME variable pointing to Java 1.8. However, with EAP 7.2 Java 11 is also supported (EAP7-431). When user installs a package of Java 11 (e.g. Oracle JDK 11) which provides necessary Java dependency (java >= 1:1.8) before installing EAP 7 RPMs, EAP will fail to start as required paths do not exist on the system.

These hard-coded paths JAVA_HOME and JAVAPTH are included in following files in RHEL 7 (and probably also RHEL 8) RPMs:

/usr/lib/systemd/system/eap7-standalone.service
/usr/lib/systemd/system/eap7-domain.service

We should probably point to the default java path managed by '?alternatives?' on the system as a default option '/usr/lib/jvm/jre'. So by default the system preferred java is chosen for EAP7 from RPM installation. Customer can alternate this default by its desired java requirement by modifying the followng configuration files:

/etc/opt/rh/eap7/wildfly/eap7-standalone.conf
/etc/opt/rh/eap7/wildfly/eap7-domain.conf

as described here.

NOTE: similar behaviour with default java looks to be present also on RHEL6.