}
assertNull(treeMap.floorEntry(1));
assertNull(treeMap.lowerKey(1));
assertNull(treeMap.lowerEntry(1));
assertNull(treeMap.higherKey(1));
assertNull(treeMap.higherEntry(1));
assertFalse(treeMap.containsKey(1));
assertFalse(treeMap.containsValue(1));
assertNull(treeMap.get(1));
assertNull(treeMap.pollFirstEntry());