Replace StreamResource with DownloadHandler in Collaboration Kit docs

[MatthewVaadin]

DownloadHandler is now supported by Collaboration Kit (version 6.5.0). This updates the documentation to reflect that change.

NOTE: This should not be merged until platform:24.8.5 is released

Part of vaadin/collaboration-kit#94

[github-actions]

AI Language Review

For the source code file AvatarGroupDocumentation:

1. In the imageHandler() method, the change from StreamResource to DownloadHandler is appropriate for downloading or streaming images. However, the inner lambda function directly calls the new ByteArrayInputStream(imageBytes) without checking if imageBytes might be null or empty. You may want to add a null check or error handling to prevent potential issues if the user entity does not have an image.

For the AsciiDoc documentation file:

1. Throughout the documentation, ensure that all code references to setImageProvider are updated to setImageHandler to maintain consistency with the updated Java code.
2. Review the term "ensuranceClaims" for "insuranceClaims" in the example for a potential typo.

These are the primary areas that need attention based on the changes observed.

[mstahv]

Is there some specific reason to use this odd byte[] -> ByteArrayInputStream -> use helper to write input stream to outputstream pattern here (aka DownloadHandler.fromInputStream)? I don't have the changed Collaboration Kit API at my hands, but it would be more natural to me to push the images directly to the output stream 🤔

Related thinking in this test class (although in this case that would be even simpler): https://github.com/parttio/addon-demos/blob/main/src/main/java/org/example/otherexamples/NewDownloadAPI.java

[MatthewVaadin]

@mstahv I was adapting the existing example to use the new DoenloadHandler using this as a reference. The intent was to show that this can be used for dynamic resources, so maybe we should use a dynamic example rather than implying that it should be used for static resources?

[mstahv]

Yeah, I agree a dynamically generated example would be best and in that case it is even more clearer that you want to use the previous "Using DownloadEvent And Lambda Expression" approach that I was referring to 👍