Support Spring Boot 4

[Mistborn94]

Fixes #4345

What does this PR do?

Implements support for Spring Boot 4 / Spring Framework 7

Checklist

• This is an enhancement of existing features, or a new feature in existing plugins
  • I have updated CHANGELOG.next-release.md
  • I have added tests that prove my fix is effective or that my feature works
  • Added an API method or config option? Document in which version this will be introduced
  • I have made corresponding changes to the documentation
• This is a bugfix
  • I have updated CHANGELOG.next-release.md
  • I have added tests that would fail without this fix
• This is a new plugin
  • I have updated CHANGELOG.next-release.md
  • My code follows the style guidelines of this project
  • I have made corresponding changes to the documentation
  • I have added tests that prove my fix is effective or that my feature works
  • New and existing unit tests pass locally with my changes
  • I have updated supported-technologies.md
  • Added an API method or config option? Document in which version this will be introduced
  • Added an instrumentation plugin? Describe how you made sure that old, non-supported versions are not instrumented by accident.
• This is something else
  • I have updated CHANGELOG.next-release.md

[cla-checker-service]

💚 CLA has been signed

[github-actions]

🤖 GitHub comments

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[github-actions]

🔍 Preview links for changed docs

• docs/reference/supported-technologies.md

[andrzej1990m]

What is the status of this PR @Mistborn94 ? Many developers need these support.

[Mistborn94]

It is ready to review - I just need this project's mainainers to review and merge.

[jackshirazi]

it's failing tests

[Mistborn94]

@jackshirazi These tests were also failing on master when I checked last week and is also failing on other open PRs with the dame error :( I'm not sure what I can do to fix it...

[andrzej1990m]

These PR looks really good. You have added a lot of tests and fixed main problem with headers which we also noticed. Nice! 👍
@jackshirazi could you help with these problems with tests? We really, really need these changes and a new version of apm agent which comes with support for sb 4 :(

[pavleec]

Hi, I can't wait to merge this PR either. @jackshirazi 🥺

[michbeck100]

We are currently moving our applications to spring boot 4 and we are using the latest version 1.55.4 of the APM agent already. Do you think this will be merged and released soon?

[github-actions]

Vale Linting Results

Summary: 2 warnings, 10 suggestions found

⚠️ Warnings (2)

File	Line	Rule	Message
docs/reference/supported-technologies.md	85	Elastic.DontUse	Don't use 'Note that'.
docs/reference/supported-technologies.md	86	Elastic.DontUse	Don't use 'Note that'.

💡 Suggestions (10)

File	Line	Rule	Message
docs/reference/supported-technologies.md	78	Elastic.Wordiness	Consider using 'because' instead of 'Since'.
docs/reference/supported-technologies.md	80	Elastic.Wordiness	Consider using 'because' instead of 'since'.
docs/reference/supported-technologies.md	81	Elastic.WordChoice	Consider using 'start, run' instead of 'Boot', unless the term is in the UI.
docs/reference/supported-technologies.md	81	Elastic.Wordiness	Consider using 'because' instead of 'since'.
docs/reference/supported-technologies.md	82	Elastic.Wordiness	Consider using 'because' instead of 'since'.
docs/reference/supported-technologies.md	83	Elastic.Wordiness	Consider using 'because' instead of 'since'.
docs/reference/supported-technologies.md	84	Elastic.WordChoice	Consider using 'start, run' instead of 'Boot', unless the term is in the UI.
docs/reference/supported-technologies.md	84	Elastic.Wordiness	Consider using 'because' instead of 'since'.
docs/reference/supported-technologies.md	85	Elastic.Wordiness	Consider using 'because' instead of 'since'.
docs/reference/supported-technologies.md	86	Elastic.Wordiness	Consider using 'because' instead of 'since'.

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