SYNCASE-2653 Avoid reindexing unchanged attachments

[ebeutler]

Questions I had and the AI answers I got:

1. I had a look at the changes and have seen you used getRenderedTitle to compare the titles. Is there a reason the title should be rendered instead of just comparing the results of getTitle?

Yes. AttachmentData indexes doc.getRenderedTitle(...), not getTitle() (abstractdocumentdata.java:110).

Using getTitle() would miss changes when the title is empty and derived from content, or when unchanged title markup renders differently due to document data. Comparing the indexed value avoids stale attachment titles; the cost is only two renders per update.

Is this actually something that can even happen in celements? I'm not sure ...

2. In line 51 only the docRef is returned for indexing. Shouldn't the one attachment that was uploaded / deleted also be part of the stream?

No. The changed attachment is queued separately:

• xwiki.java:5678 converts attachment diffs into added/updated/deleted events.
• queueattachmenteventconverter.java:47 queues exactly that attachment.
• Deletions become delete tasks through isDeleteEvent().

Adding it to the document stream would duplicate uploads/updates, while deleted attachments are no longer in the document list anyway. Line 51 is intentional.