Custom dav properties with namespaces are rendered incorrectly

[dpakach]

Describe the bug

Custom dav properties in dav response are rendered incorrectly

Steps to reproduce

Steps to reproduce the behavior:

https://github.com/owncloud/core/blob/076ddc7dc430e1e80d23b374d13c73f199cb398a/tests/acceptance/features/apiWebdavProperties1/setFileProperties.feature#L24

Expected behavior

custom dav properties with namespace rendered as in oc10

<?xml version="1.0" encoding="UTF-8"?>
<d:multistatus xmlns:d="DAV:" xmlns:oc="http://owncloud.org/ns" xmlns:s="http://sabredav.org/ns">
   <d:response>
      <d:href>/core/remote.php/dav/files/Alice/testcustomprop.txt</d:href>
      <d:propstat>
         <d:prop>
            <x1:very-custom-prop xmlns:x1="http://whatever.org/ns">
               <x2:foo xmlns:x2="http://bar" />
            </x1:very-custom-prop>
         </d:prop>
         <d:status>HTTP/1.1 200 OK</d:status>
      </d:propstat>
   </d:response>
</d:multistatus>

Actual behavior

dav properties are rendered incorrectly in the xml

<?xml version="1.0" encoding="UTF-8"?>
<d:multistatus xmlns:d="DAV:" xmlns:oc="http://owncloud.org/ns" xmlns:s="http://sabredav.org/ns">
   <d:response>
      <d:href>/remote.php/dav/files/Alice/testcustomprop.txt</d:href>
      <d:propstat>
         <d:prop>
            <very-custom-prop xmlns="http://whatever.org/ns">&lt;foo xmlns='http://bar'/&gt;</very-custom-prop>
         </d:prop>
         <d:status>HTTP/1.1 200 OK</d:status>
      </d:propstat>
   </d:response>
</d:multistatus>

Setup

Please describe how you started the server and provide a list of relevant environment variables.

OCIS_VERSION=git
BRANCH=master
STORAGE_FRONTEND_UPLOAD_DISABLE_TUS=false

Additional context

Add any other context about the problem here.

[saw-jan]

The behavior still exists: 1. PROPPATCH

curl -XPROPPATCH "https://localhost:9200/remote.php/dav/files/admin/file.txt" \
-d'<?xml version="1.0"?><d:propertyupdate xmlns:d="DAV:" xmlns:oc="http://owncloud.org/ns"><d:set><d:prop><x1:very-custom-prop xmlns:x1="http://whatever.org/ns">veryCustomPropValue</x1:very-custom-prop></d:prop></d:set></d:propertyupdate>' \
-u admin:admin -vk  | xmllint --format -

Actual:

<d:prop>
    <very-custom-prop xmlns="http://whatever.org/ns"/>
</d:prop>

Expected:

 <d:prop>
    <x1:very-custom-prop xmlns:x1="http://whatever.org/ns"/>
</d:prop>

2. PROPFIND

curl -XPROPFIND "https://localhost:9200/remote.php/dav/files/admin/file.txt" \
-d'<?xml version="1.0"?><d:propfind xmlns:d="DAV:" xmlns:oc="http://owncloud.org/ns" xmlns:ocs="http://open-collaboration-services.org/ns" xmlns:x1="http://whatever.org/ns"><d:prop><x1:very-custom-prop/></d:prop></d:propfind>' \
-u admin:admin -vk  | xmllint --format -

Actual:

<d:prop>
    <very-custom-prop xmlns="http://whatever.org/ns">
        &lt;foo xmlns="http://bar"/&gt;
    </very-custom-prop>
</d:prop>

Expected:

<d:prop>
    <x1:very-custom-prop xmlns:x1="http://whatever.org/ns">
        <x2:foo xmlns:x2="http://bar"/>
    </x1:very-custom-prop>
</d:prop>

[saw-jan]

CC @micbar @ScharfViktor