There are various checks in WildFly Core code base like:

if (JdkUtils.getJavaSpecVersion() >= 11) // do something
if (JvmElement.getJVMMajorVersion() < 9) // do something
if (PlatformMBeanUtil.JVM_MAJOR_VERSION > 6) // do something
if (PlatformMBeanUtil.JVM_MAJOR_VERSION < 7) // do something

Since JDK 11 is minimum JDK requirement all these checks can be safely removed and coded adjusted.