import org.jetbrains.annotations.NotNull; class Test { private static void test(@NotNull Object foo) { assert foo != null; } private static void test2(@NotNull Object foo) { if (foo == null) { throw new IllegalArgumentException(); } } private static void test3(@NotNull Object foo) { if (foo == null) throw new IllegalArgumentException(); } private static void test4(@NotNull Object foo) { if (<warning descr="Condition 'foo != null' is always 'true'">foo != null</warning>) throw new IllegalArgumentException(); } }