excludedProjects.addAll(
                    projectSelector.getRequiredProjectsBySelectors(request, allProjects, requiredSelectors));
            excludedProjects.addAll(
                    projectSelector.getOptionalProjectsBySelectors(request, allProjects, optionalSelectors));

            result = new ArrayList<>(projects);
            result.removeAll(excludedProjects);

            if (result.isEmpty()) {

        // We intentionally ignore the results of this method.
        // As a side effect it will log the optional projects that could not be resolved.
        projectSelector.getOptionalProjectsBySelectors(request, session.getAllProjects(), allOptionalSelectors);
    }

    /**
     * Check whether any of the requested optional profiles were not activated or deactivated.
     * @param session the Maven session.