BUG: Transformation "ChangeNodeType" does not work on documents in Neos 9, because it believes that ContentCollection is not an allowed child node for Documents

[theDex]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

When executing a node migration with the transformation "ChangeNodeType" on a Document-NodeType it throws an error that ContentCollections are not an allowed child node for the new document, even if they specify a child node 'main' with that type.

If you set the option forceDeleteNonMatchingChildren: true it works as intended and does not delete the ContentCollection, but it would be preferable to not have to set that for every node migration that includes Document-NodeTypes.

It seems the process of transforming correctly checks for named child nodes (like 'main'), but the check beforehand only checks if a NodeType is generally allowed as a childNode of the NodeType you're migrating to.

Expected Behavior

The check before the ChangeNodeType-Transformation should correctly check for named child nodes when it tries to determine if a child node is allowed in the new NodeType.

Steps To Reproduce

I guess it is also reproducable in other ways, but the easiest for me was to install an fresh Neos (ddev) with the neos/demo SitePackage.

Then I added a new NodeType:

'Neos.Demo:Document.Page2':
  superTypes:
    'Neos.Demo:Document.Page': true
  ui:
    label: 'Page 2'

prototype(Neos.Demo:Document.Page2) < prototype(Neos.Demo:Document.Page)

And a simple NodeMigration:

comments: 'Test Migration'
migration:
  - filters:
      - type: 'NodeType'
        settings:
          nodeType: 'Neos.Demo:Document.Page'

    transformations:
      - type: 'ChangeNodeType'
        settings:
          newType: 'Neos.Demo:Document.Page2'

If you try to run the migration the following error is thrown:

Comments
  Test Migration
Node type "Neos.Demo:Collection.Content.Main" is not allowed for child nodes of type Neos.Demo:Document.Page2

  Type: Neos\ContentRepository\Core\SharedModel\Exception\NodeConstraintException
  Code: 1707561400
  File: Packages/Libraries/neos/contentrepository-core/Classes/Feature/Common/Const
        raintChecks.php
  Line: 340

Environment

- Flow: 9.1.0
- Neos: 9.1.1
- PHP: 8.3.27

Anything else?

No response

[markusguenther]

Can verify that :/