This program fails to compile:

 interface CheckedSupplier<T extends Throwable, R> {
    R get() throws T;

    static <T extends Throwable, R> CheckedSupplier<T, R> checked(CheckedSupplier<T, R> checkedSupplier) {
        return checkedSupplier;
    }

    static void main(String[] args) {
        checked(() -> null).get();
    }
}