[Bug]: Support PHP8.1 with swiftmailer

[creopard]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• Nextcloud Server is running on 64bit capable CPU, PHP and OS.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

This is a remainder for the open issue with the PHP 8.1 compatibility and the 3rd party addon "swiftmailer" found by @VVD and requested by @ChristophWurst

The issue is described here:
#29287 (comment)

The solution is already available, but not yet implemented (as with NC 25.0.1):
The existing commit swiftmailer/swiftmailer@ee8a1d9 is not yet integrated into https://github.com/nextcloud/3rdparty/tree/master/swiftmailer/swiftmailer

Steps to reproduce

1. Use PHP 8.1
2. Send a test email from the settings/admin
3. The email will be sent successfully. However, you'll find the following error message in the Nextcloud log:
   Error: strtolower(): Passing null to parameter #1 ($string) of type string is deprecated at /home/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Transport/EsmtpTransport.php#144

Expected behavior

No deprecated error message should be thrown.

Installation method

Community Web installer on a VPS or web space

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Apache (supported)

Database engine version

MySQL

Is this bug present after an update or on a fresh install?

Updated to a major version (ex. 22.2.3 to 23.0.1)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

{
    "system": {
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "***REMOVED SENSITIVE VALUE***"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "25.0.1.1",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "default_phone_region": "DE",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpsecure": "ssl",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "updater.release.channel": "stable",
        "trashbin_retention_obligation": "10,30",
        "versions_retention_obligation": "10,30",
        "loglevel": 0,
        "cron_log": true,
        "log_rotate_size": 5242880,
        "dbdriveroptions": {
            "1002": "SET wait_timeout = 28800"
        },
        "maintenance": false,
        "theme": "",
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "allowNightlyUpdates": [],
        "mail_sendmailmode": "smtp",
        "mysql.utf8mb4": true,
        "app_install_overwrite": [
            "bruteforcesettings"
        ]
    }
}

List of activated Apps

Enabled:
  - activity: 2.17.0
  - bruteforcesettings: 2.5.0
  - calendar: 4.1.0
  - cloud_federation_api: 1.8.0
  - comments: 1.15.0
  - contacts: 5.0.1
  - dashboard: 7.5.0
  - dav: 1.24.0
  - federatedfilesharing: 1.15.0
  - files: 1.20.1
  - files_downloadactivity: 1.15.0
  - files_rightclick: 1.4.0
  - files_sharing: 1.17.0
  - files_trashbin: 1.15.0
  - files_versions: 1.18.0
  - firstrunwizard: 2.14.0
  - logreader: 2.10.0
  - lookup_server_connector: 1.13.0
  - nextcloud_announcements: 1.14.0
  - notifications: 2.13.1
  - oauth2: 1.13.0
  - password_policy: 1.15.0
  - passwords: 2022.11.20
  - privacy: 1.9.0
  - provisioning_api: 1.15.0
  - recommendations: 1.4.0
  - related_resources: 1.0.3
  - serverinfo: 1.15.0
  - settings: 1.7.0
  - sharebymail: 1.15.0
  - systemtags: 1.15.0
  - text: 3.6.0
  - theming: 2.0.1
  - twofactor_backupcodes: 1.14.0
  - updatenotification: 1.15.0
  - viewer: 1.9.0
  - workflowengine: 2.7.0
Disabled:
  - admin_audit
  - circles: 23.0.0
  - contactsinteraction: 1.5.0
  - encryption
  - federation: 1.13.0
  - files_external
  - files_pdfviewer: 2.4.0
  - photos: 1.6.0
  - support: 1.0.0
  - survey_client: 1.2.0
  - suspicious_login
  - twofactor_totp
  - user_ldap
  - user_status: 1.3.1
  - weather_status: 1.0.0

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

{"reqId":"Fmga0R2gFKqyeS9y47ov","level":3,"time":"2022-11-09T13:37:30+00:00","remoteAddr":"IPADDRESS_REMOVED","user":"USERID-REMOVED","app":"PHP","method":"POST","url":"/index.php/settings/admin/mailtest","message":"strtolower(): Passing null to parameter #1 ($string) of type string is deprecated at /home/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Transport/EsmtpTransport.php#144","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:106.0) Gecko/20100101 Firefox/106.0","version":"25.0.1.1","exception":{"Exception":"Error","Message":"strtolower(): Passing null to parameter #1 ($string) of type string is deprecated at /home/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Transport/EsmtpTransport.php#144","Code":0,"Trace":[{"function":"onError","class":"OC\\Log\\ErrorHandler","type":"::"},{"file":"/home/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Transport/EsmtpTransport.php","line":144,"function":"strtolower"},{"file":"/home/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/SmtpTransport.php","line":43,"function":"setEncryption","class":"Swift_Transport_EsmtpTransport","type":"->"},{"file":"/home/lib/private/Mail/Mailer.php","line":267,"function":"__construct","class":"Swift_SmtpTransport","type":"->"},{"file":"/home/lib/private/Mail/Mailer.php","line":254,"function":"getSmtpInstance","class":"OC\\Mail\\Mailer","type":"->"},{"file":"/home/lib/private/Mail/Mailer.php","line":180,"function":"getInstance","class":"OC\\Mail\\Mailer","type":"->"},{"file":"/home/apps/settings/lib/Controller/MailSettingsController.php","line":170,"function":"send","class":"OC\\Mail\\Mailer","type":"->"},{"file":"/home/lib/private/AppFramework/Http/Dispatcher.php","line":225,"function":"sendTestMail","class":"OCA\\Settings\\Controller\\MailSettingsController","type":"->"},{"file":"/home/lib/private/AppFramework/Http/Dispatcher.php","line":133,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/home/lib/private/AppFramework/App.php","line":172,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/home/lib/private/Route/Router.php","line":298,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/home/lib/base.php","line":1047,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/home/index.php","line":36,"function":"handleRequest","class":"OC","type":"::"}],"File":"/home/lib/private/Log/ErrorHandler.php","Line":92,"CustomMessage":"--"}}

Additional info

No response

[ChristophWurst]

cc @come-nc

[come-nc]

cc @come-nc

Done for master, is that needed on stable* as well?

[ChristophWurst]

Stable25 would make sense