accumulate with sliding window and other LHS condition

declare Measurement
	@role(event)
end

rule "Init Counter last 1h"
agenda-group "USERSPACE"
salience 1
no-loop
when
	not Counter( name == "Counter last 1h" )
then
	Counter c = new Counter("Counter last 1h", 0);
	insert(c);
	System.out.println("RHS Init Counter last 1h " + c);
end

rule "Update Counter last 1h"
agenda-group "USERSPACE"
no-loop
when
	accumulate( $token : Measurement() over window:time( 1h ) ;
 				$val : count($token)
 			   )
 	$cv1 : Counter( name == "Counter last 1h", value != $val.doubleValue() )
then
	int count = $val.intValue();
	$cv1.setValue(count);
	update($cv1);
	System.out.println("RHS Update Counter last 1h : "+$cv1);
end

advance(clock, 1, TimeUnit.MINUTES);
insert(session, new Measurement("voltage", "220"));
fire(session);

advance(clock, 1, TimeUnit.MINUTES);
insert(session, new Measurement("voltage", "221"));
fire(session);

LOG.info("Final checks");
Counter counter = (Counter) session.getObjects(counterFilter).iterator().next();         // I'm taking a shortcut as for this reproducer I know there is only 1 Counter in WM
assertEquals("I've inserted 2 Measurement within the hour ", 2, counter.getValue(), 0);