* @return an immutable collection of attached artifacts, may be empty if no artifacts
     *         have been attached yet
     * @throws IllegalArgumentException if the project is null
     * @see #getAllArtifacts(Project)
     */
    @Nonnull
    Collection<ProducedArtifact> getAttachedArtifacts(@Nonnull Project project);

    /**

        return Collections.unmodifiableCollection(attached);
    }

    @Override
    @Nonnull
    public Collection<ProducedArtifact> getAllArtifacts(@Nonnull Project project) {
        requireNonNull(project, "project cannot be null");
        ArrayList<ProducedArtifact> result = new ArrayList<>(2);
        result.addAll(project.getArtifacts());