[HttpKernel] fixed regression introduced in 2.4 in the base DataCollector class. Added more unit tests coverage for the RequestDataCollector object.
bug #9617 [HttpKernel] Http kernel regression fix (hhamon)

This PR was merged into the 2.4 branch.

Discussion
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[HttpKernel] Http kernel regression fix

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | ~
| License       | MIT
| Doc PR        | ~

Commits
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d1e5006 [HttpKernel] fixed regression introduced in 2.4 in the base DataCollector class. Added more unit tests coverage for the RequestDataCollector object.