Just a fair reminder: by using `setOf` or `emptySe...

# announcements

[alexey.tsvetkov]

Just a fair reminder: by using setOf or emptySet<Long>().plus(5) you don't get an immutable set; instead you get an immutable reference to a mutable set. You can check that by printing java class of an expression returned by setOf for example. On the JVM platform that would be LinkedHashMap, which means that the underlying set can be mutated from java.