Making two types have the same qualifier

Collection.remove throws a NullPointerException if its argument is null and the collection does not support null elements. Thus, remove should take a nullable parameter for a Collection containing nullable elements, and remove should take a non-null parameter for a Collection containing non-null elements.

Here is the desired effect:

  Collection<@Nullable String> cNullable;
  cNullable.remove(null);  // OK
  Collection<@NonNull String> cNonnull;
  cNonnull.remove(null);  // compile-time error

A way to annotate this would be:

interface Collection<E> {
  boolean remove(@NullnessOf(E) Object o) { ... }
}

Thus, the Nullness Checker needs to support an annotation such as @NullnessOf.
(Unless there is some other way to achieve the same effect.)

Start with the Nullness Checker and investigate how it could express a qualifier derived from a collection's element type. Compare the proposed @NullnessOf behavior with the two Collection examples; done means nullable collections accept null in remove while non-null collections reject it at compile time.