@Override
    public SfmSketchState createGroupedState()
    {
        return new GroupedSfmSketchState();
    }
@Test
    public void testCreateGroupedStateEmpty()
    {
        SfmSketchState state = factory.createGroupedState();
        assertNull(state.getSketch());
        int instanceSize = 40;
        long bigObjectSize = (new ObjectBigArray<>()).sizeOf();
        assertTrue(state.getEstimatedSize() >= instanceSize + bigObjectSize, format("Estimated memory size was %d", state.getEstimatedSize()));
    }