keySet = navigableMap_startExcluded_endExcluded.navigableKeySet();
assertEquals(firstKey1, keySet.last());
keySet = navigableMap_startExcluded_endIncluded.navigableKeySet();
assertEquals(firstKey2, keySet.last());
keySet = navigableMap_startIncluded_endExcluded.navigableKeySet();
assertEquals(firstKey1, keySet.last());
keySet = navigableMap_startIncluded_endIncluded.navigableKeySet();