Issue ssh key manager - error messages

[Brujo]

Plesk Onyx 17.8.11 Update #13
OS version: CentOS 7.5.1804
SSH Key Manager Version: 1.2.0-3

When I access the plesk panel -> domain > sshkey (top right box) it generates in the /var/log/plesk/panel.log always the following log entry:

[2018-06-29 06:27:09.147] ERR [1] PHP Warning: Declaration of Modules_SshKeys_FileManager::mkdir($path, $permissions) should be compatible with pm_FileManager::mkdir($dirname, $perms = '0755', $recursively = false); File: /usr/local/psa/admin/plib/modules/ssh-keys/library/FileManager.php, Line: 4

but I can not detect any misconduct, so it just fill up the log