Is an H2 database capable of executing an SQL query on an over clause with an Aggregate function?

SQL like

SELECT empno, deptno, 
COUNT(*) OVER (PARTITION BY deptno) DEPT_COUNT FROM emp WHERE deptno IN (20, 30);

very helpful.

I'm just wondering, in H2, how do we implement a similar function? Perhaps creating a java procedure will work. But will this feature be inside the H2 database roadmap?