set.add("Key#1000");
assertTrue("Key#1000 was removed", set.retainAll(set2));
assertEquals("Size == 1", 1, set.size());
assertTrue("set contains [Key#1000]", set.containsAll(set2));
set.clear();
assertEquals("Size == 0", 0, set.size());
assertEquals("Size is empty", true, set.isEmpty());
for(int n = 0; n < 1000; n ++)
{
String key = keys[n];