organization_folders/lib/Model/UserPrincipal.php

<?php

namespace OCA\OrganizationFolders\Model;

use OCP\IUserManager;
use \OCP\IUser;

use OCA\OrganizationFolders\Enum\PrincipalType;

class UserPrincipal extends Principal {
    private ?IUser $user;

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

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

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

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