Refactor/remove custom MultipartFileSender to use Spring Boot Range requests

[jonas-atmire]

References

• Fixes Refactor/remove custom MultipartFileSender to use Spring Boot Range requests #2983
• Fixes Support for process output on detail page dspace-angular#827

Description

The custom MultipartFileSender was completely bypassing Spring Security & Spring automated tools.
This PR makes sure that we lean more towards the 'default' usages of the previously mentioned Spring Boot etc.

Instructions for Reviewers

Please add a more detailed description of the changes made by your PR. At a minimum, providing a bulleted list of changes in your PR is helpful to reviewers.

List of changes in this PR:

• MultipartFileSender is renamed to HttpHeadersInitializer to more correctly reflect the functionality/usage
• HttpHeadersInitializer been 'changed' to now only initialise the HTTPHeaders, apart from trying to handle a whole bunch of code itself (So that we can rely on the spring framework to handle the MultiPart file sending)
  • The HTTPHeaders will be used in the ResponseEntity given by any methods that need to reply with a downloaded file
• The SitemapRestController is altered to adhere to the guidelines of returning a ResponseEntity as well
• the BitstreamRestController returns a new ResponseEntity for the bitstream resource to properly handle the multipart file sending

Testing steps using REST

• Setup the related REST code
• Trigger a script that keeps output in a file
• Trigger a GET call to that particular output bitstream (With an origin header)
• Check that the header "Access-Control-Allow-Origin:" is returned as expected

Testing steps using Angular

• Setup the related REST code
• Setup the following Angular PR
• Make sure to trigger a script that keeps output in a file.
• Try to download that particular output bitstream
• The bitstream should be properly 'downloaded', no CORS error should be logged, and the information of the logs should be shown in the UI

Checklist

This checklist provides a reminder of what we are going to look for when reviewing your PR. You need not complete this checklist prior to creating your PR (draft PRs are always welcome). If you are unsure about an item in the checklist, don't hesitate to ask. We're here to help!

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & integration tests). Exceptions may be made if previously agreed upon.
• My PR passes Checkstyle validation based on the Code Style Guide.
• My PR includes Javadoc for all new (or modified) public methods and classes. It also includes Javadoc for large or complex private methods.
• My PR passes all tests and includes new/updated Unit or Integration Tests based on the Code Testing Guide.
• If my PR includes new, third-party dependencies (in any pom.xml), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR modifies the REST API, I've linked to the REST Contract page (or open PR) related to this change.

[tdonohue]

@jonas-atmire : I gave this a code review & some basic testing today. First off, the code looks good.. there's just some missing JavaDocs & a few inline questions below that require cleanup.

I also tested this from commandline (using the same commands that I reported previously didn't work in this comment)... and I've found this seems to work great! I'm now seeing the headers that are automatically added by Spring Security like Access-Control-Allow-Origin and Access-Control-Expose-Headers. Previously, those were missing.

I've not yet had a chance to test it with the corresponding Angular UI PR (DSpace/dspace-angular#827) simply because that PR is outdated & needs a rebase to make it easier to test.

Overall this looks/works great. So, I'm only requesting JavaDocs additions / minor cleanup here. Once the Angular PR is ready again, I'll do a test of both together & then I expect to approve both. Thanks!

[crosenbeck]

@jonas-atmire Thank you for your hard work on this PR and the changes that were made to this PR. It looks good to me as long as @tdonohue requested changes have been made.

[tdonohue]

👍 @jonas-atmire and @Raf-atmire : Code looks great now. I also tested this today with the frontend PR (DSpace/dspace-angular#827) and it all works perfectly. Thanks again!