Test components using their lowest possible deps
minor #12542 Test components using their lowest possible deps (nicolas-grekas)

This PR was squashed before being merged into the 2.3 branch (closes #12542).

Discussion
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Test components using their lowest possible deps

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

Once https://github.com/composer/composer/pull/3450 is merged, we'll see if our deps are correct, and ensure that is kept over time by testing each component with its lowest possible deps.

Commits
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25fef27 Test components using their lowest possible deps
Fix return phpdoc
[2.3] Docblocks should not be followed by a blank line
minor #12993 [2.3] Docblocks should not be followed by a blank line (GrahamCampbell)

This PR was squashed before being merged into the 2.3 branch (closes #12993).

Discussion
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[2.3] Docblocks should not be followed by a blank line

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

There should be no blank line(s) between phpdocs that document properties, interfaces, classes, functions, or traits. This pull request was a test run of a new php-cs-fixer: https://github.com/FriendsOfPHP/PHP-CS-Fixer/pull/864.

Commits
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4e7ba1b [2.3] Docblocks should not be followed by a blank line
minor #12985 [HttpFoundation] Fix return phpdoc (Koc)

This PR was merged into the 2.3 branch.

Discussion
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[HttpFoundation] Fix return phpdoc

| Q             | A
| ------------- | ---
| Bug fix?      | tiny (for IDE autocompletion)
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

What about using `self` or `static` keyword for this?

Commits
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9af2d81 Fix return phpdoc
[FrameworkBundle] fix cache:clear command
CS: There should be no empty lines following phpdocs
minor #13011 CS: There should be no empty lines following phpdocs (keradus)

This PR was merged into the 2.3 branch.

Discussion
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CS: There should be no empty lines following phpdocs

Commits
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143f900 CS: There should be no empty lines following phpdocs
add a limit and a test to FlattenExceptionTest.
bug #13004 add a limit and a test to FlattenExceptionTest. (Daniel Wehner)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #13004).

Discussion
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add a limit and a test to FlattenExceptionTest.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #13003
| License       | MIT
| Doc PR        |

Commits
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c6bcf05 add a limit and a test to FlattenExceptionTest.
bug #12999 [FrameworkBundle] fix cache:clear command (nicolas-grekas)

This PR was merged into the 2.3 branch.

Discussion
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[FrameworkBundle] fix cache:clear command

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12893
| License       | MIT
| Doc PR        | -

Reading comment on #12893 stating that using absolute paths works around the pb, I tried using realpath(),
and it works!
Pending work on #12955 can be done quietly now.

Commits
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a14153a [FrameworkBundle] fix cache:clear command
fixed CS