SwitchTest.java

import org.checkerframework.checker.nullness.qual.*;

public class SwitchTest {
    public static void main(String[] args) {
        //:: error: (switching.nullable)
        switch (getNbl()) {
            case X:
                System.out.println("X");
                break;
            default:
                System.out.println("default");
        }
    }

    public static void goodUse() {
        switch (getNN()) {
            case X:
                System.out.println("X");
                break;
            default:
                System.out.println("default");
        }
    }

    public static @Nullable A getNbl() {
        return null;
    }

    public static A getNN() {
        return A.X;
    }

    public static enum A {
        X
    }
}