Changing language of container will only change it also for its own children (not recursive)

[github1maxserv]

If there are nested containers and the language of the outer container is changed only direct children will be modified as well. Grandchildren and further levels are ignored.

Use case

Part of a migration from gridelements to containers was to convert containers with language "All languages" to properly translated content in connected mode.

Location of problem

\B13\Container\Hooks\Datahandler\DatamapBeforeStartHook::datamapForChildrenChangeContainerLanguage() only adds direct children to the array of elements that need to be modified.

How to reproduce

Use the Page module to created nested containers with content elements at the lowest level. Switch to the List module (Container doesn't like All languages elements very much). Edit the outer most container and change the language to "All languages". Verify that only the direct children of the modified container also have their language setting changed.

[github1maxserv]

A solution could be to recursively add children:

        if (count($datamapForLocalizations['tt_content']) > 0) {
            $datamap['tt_content'] = array_replace(
                $datamap['tt_content'],
                $this->datamapForChildrenChangeContainerLanguage($datamapForLocalizations)['tt_content']
            );
        }
        return $datamap;

An alternative could be to add a loop around most of the function to repeat the process until no more children are found.