organization_folders/lib/Model/GroupPrincipal.php

<?php

namespace OCA\OrganizationFolders\Model;

use OCP\IGroupManager;
use \OCP\IGroup;

use OCA\OrganizationFolders\Enum\PrincipalType;

class GroupPrincipal extends Principal {
    private ?IGroup $group;

    public function __construct(
        private IGroupManager $groupManager,
        private string $id,
	) {
        try {
            $this->group = $this->groupManager->get($id);
            $this->valid = !is_null($this->group);
        } catch (\Exception $e) {
            $this->valid = false;
        }
    }

    public function getType(): PrincipalType {
		return PrincipalType::GROUP;
	}

    public function getId(): string {
		return $this->id;
	}

    public function getFriendlyName(): string {
        return $this->group?->getDisplayName();
    }
}