Check wasNull with JDBC CallableStatement

Suppose you have a CallableStatement which calls a database function and returns an integer. You would register the out parameter by
cs.registerOutParameter(1, Types.Integer);
cs.execute();

Let's say you want to check if NULL is returned as below.
Integer result = cs.getInt(1);
if (result == null) {
// NULL
}

This is wrong because result will be 0 (zero), instead of null, if NULL is returned from the database function. This is documented here.

The right way to check is to use wasNull.
Integer result = cs.getInt(1);
if (cs.wasNull) {
// NULL
}