import org.checkerframework.checker.nullness.qual.*; public class Simple2 { @NonNull String f; public Simple2() { //:: error: (method.invocation.invalid) test(); f = "abc"; } public void test() { System.out.println(f.toLowerCase()); } public void a(Simple2 arg) { @Nullable String s = null; //:: error: (dereference.of.nullable) s.hashCode(); } public static void main(String[] args) { new Simple2(); } }