In the maven-antrun-plugin configuration in pom.xml, the JVM system property -Dlog4j2.disable.jmx=true is incorrectly passed via <arg line> instead of <jvmarg>. This causes it to be passed as an argument to XMLSchemaGenerator.main(String[] args) rather than to the JVM.

The argument parser in XMLSchemaGenerator.main() only recognizes -o. When it encounters -Dlog4j2.disable.jmx=true as the first argument, it prints the usage message and returns immediately — before the schema file is written.

As a result, target/schema/ only contains fork-stacks.xsd and relay.xsd (which are copied from conf/), but the generated jgroups-<version>.xsd is missing.