create any immutable collection • If the items are known a priori, use the .of factory method ImmutableList.of 3, 1, 4, 1, 5, 9 # [3, 1, 4, 1, 5, 9] ImmutableSet.of 3, 1, 4, 1, 5, 9 # [3, 1, 4, 5, 9] ImmutableSortedSet.of 'foo', 'bar', 'baz' # [bar, baz, foo] ImmutableMap.of :foo, 3, :bar, 1, :baz, 4 # {foo=3, bar=1, baz=4} ImmutableMap.of :foo, 3, :foo, 1 # IllegalArgumentException • For unsorted collections, the insertion order is used o Ordering not unlike LinkedHashMap/LinkedHashSet