@Test
    public void assertClearChildrenCleanupTest() {
        populateSpanTree();
        root.clearChildren();
        tree.cleanup();
        Iterator<Annotation> iter =tree.iterator();
        assertFalse(iter.hasNext());
        assertEquals(0, tree.numAnnotations());
    }
@author <a href="mailto:mpraveen@yahoo-inc.com">Praveen Mohan</a>

This test covers all possible scenarios in SpanTree.
document/src/test/java/com/yahoo/document/annotation/SpanTreeAdvTest.java