* required selectors.
 */
public final class ProjectSelector {
    private static final Logger LOGGER = LoggerFactory.getLogger(ProjectSelector.class);

    public Set<MavenProject> getActiveProjects(
            MavenExecutionRequest request,
            List<MavenProject> projects,
            List<ProjectActivation.ProjectActivationSettings> projectSelectors)
            throws MavenExecutionException {

        if (!requiredSelectors.isEmpty() || !optionalSelectors.isEmpty()) {
            Set<MavenProject> selectedProjects =
                    projectSelector.getActiveProjects(request, allSortedProjects, projectActivation.getActivations());

            // it can be empty when an optional project is missing from the reactor, fallback to returning all projects