GenericArgs2.java

import java.io.*;
import java.util.HashMap;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.*;

class Cell<T extends @Nullable Object> {
    void add(T arg) {}
}

class GenericArgs2 {
    static <F extends Object> void test1(Cell<F> collection) {
        //:: error: (argument.type.incompatible)
        collection.add(null); // should fail
    }

    static <F extends @Nullable Object> void test2(Cell<F> collection) {
        //:: error: (argument.type.incompatible)
        collection.add(null); // should fail
    }

    static void test3(Cell<@Nullable Object> collection) {
        collection.add(null); // valid
    }
    // No "<F super Object>" version of the above, as that is illegal in Java.

    static class InvariantFilter {}

    static class Invariant {}

    HashMap<Class<? extends InvariantFilter>, Map<Class<? extends Invariant>, Integer>> filter_map1;
    MyMap<@Nullable Class<? extends InvariantFilter>, Map<Class<? extends Invariant>, Integer>>
            filter_map2;

    public GenericArgs2(
            HashMap<Class<? extends InvariantFilter>, Map<Class<? extends Invariant>, Integer>>
                    filter_map1,
            MyMap<
                            @Nullable Class<? extends InvariantFilter>,
                            Map<Class<? extends Invariant>, Integer>>
                    filter_map2) {
        this.filter_map1 = filter_map1;
        this.filter_map2 = filter_map2;
    }

    class MyMap<K extends @Nullable Object, V extends @Nullable Object> {}
}