/**
* headMap returns map with keys in requested range
*/
public void testHeadMapContents() {
SnapTreeMap map = map5();
NavigableMap sm = map.headMap(four, false);
assertTrue(sm.containsKey(one));
assertTrue(sm.containsKey(two));
assertTrue(sm.containsKey(three));
assertFalse(sm.containsKey(four));
assertFalse(sm.containsKey(five));