public static VirtualSlotRef read(DataInput in) throws IOException {
        VirtualSlotRef virtualSlotRef = new VirtualSlotRef(null, Type.BIGINT, null, new ArrayList<>());
        virtualSlotRef.readFields(in);
        return virtualSlotRef;
    }
@Test
    public void read() throws IOException {
        virtualSlot.write(dos);
        virtualSlot.setRealSlots(slots);
        VirtualSlotRef v = VirtualSlotRef.read(dis);
        Assert.assertEquals(3, v.getRealSlots().size());
    }