* what phases have run dependencies in some scopes won't be included. e.g. if only compile phase has run,
     * dependencies with scope test won't be included.
     *
     * @return {@link Set} < {@link Artifact} >
     * @see #getDependencyArtifacts() to get only direct dependencies
     */
    public Set<Artifact> getArtifacts() {
        if (artifacts == null) {