<project omitting namespace declaration because this forum prevent me to include them>
	<modelVersion>4.0.0</modelVersion>
	<groupId>io.datarouter</groupId>
	<artifactId>j9mvn</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<properties>
		<maven.compiler.source>1.8</maven.compiler.source>
		<maven.compiler.target>1.8</maven.compiler.target>
	</properties>
</project>

package j9mvn;
public class Main{
	public static void main(String[] args){
		System.out.println("Hello world");
	}
}

Error: Could not find or load main class j9mvn.Main
Caused by: java.lang.ClassNotFoundException: j9mvn.Main