@Documented @Retention(value=RUNTIME) @Target(value={TYPE_USE,TYPE_PARAMETER}) @PolymorphicQualifier(value=Nullable.class) public @interface PolyNull
Any method written using PolyNull conceptually has two versions: one in which every
instance of PolyNull has been replaced by NonNull, and one in which every instance of PolyNull has been replaced by Nullable.