How to add Maven System Properties to 'Run File' Command line

[tomzi]

Normally with running a java Main Class I add System properties like this:
java -Darg1=Hi -Darg2=5 MyClass

However in NB I have no clue how to do that
.) I created a 'Run' Configuration
.) I added my system properties to the 'Run file via main()' under Actions like:

exec.args=-classpath %classpath ${packageClassName} -Darg1=Hi

but my little test program:

public class App
{
public static void main( String[] args )
{
System.out.println( "arg1=" + System.getProperty("arg1"));
}
}

would show 'arg1=null'

Any idea?