Office Import does not set default document language

Imported Office (in this case: Word) documents seem to have an empty default language, which also cannot be changed in a non-multilingual Wiki.

Maybe the importer can derive the language from the imported document's meta data / paragraph information?

Information carried over from XWIKI-20744:

On an XWIKI cloud demo instance:

When creating a page by importing an Office document (Create > "Page from Office" type), the newly created page locale is set to "None" instead of being set to the default locale as I would expect.

If I create a blank page, or a diagram page for example, the locale is correctly set (to English in my case).

It creates some confusion and side effects I think:

• Initially with Locale = None, the "Translate" button at the top and the "translations" section in the information section bottom of the page don't appear . I had to edit in wiki mode to find the translation options. They only showed up later after creating the chinese translation.
• I intially thought my original page was "english" (my default locale) and I was tanslating to Chinese. But since it was actually set to "None" and not "English",  Chinese became the new locale for the page. Took me a while to find how to get back to the original english content one (possible by clicking "Original locale : None" in the bottom information section that later showed up).
• If I create localised version by translating, there is still an existing version somewhere with locale = none. So instead of having 2 versions of my page (english, chinese) , I have 3 (english, chinese, None)

Reproducible on demo XWiki Jetty/HSQLDB 17.10.3 with LibreOffice 25.8.4.2 by importing any text document (odt, doc or docx) for page creation.

Created page with/without children will have Language = None.

Partial content of XML structure of wiki page on my end

<language/>
<defaultLanguage/>