Aliasing.java

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

public class Aliasing {
    @NonNull Object nno = new Object();
    @Nullable Object no = null;

    public static void main(String[] args) {
        Aliasing a = new Aliasing();
        Aliasing b = new Aliasing();
        m(a, b);
    }

    static void m(@NonNull Aliasing a, @NonNull Aliasing b) {
        a.no = b.nno;
        // Changing a.no to nonnull does not mean that b.no is also nonnull
        //:: error: (assignment.type.incompatible)
        b.nno = b.no;

        System.out.println("@NonNull field b.nno is: " + b.nno);
    }
}