[Form] fix CsrfProviderAdapter
bug #9423 [Form] fix CsrfProviderAdapter (Tobion)

This PR was merged into the master branch.

Discussion
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[Form] fix CsrfProviderAdapter

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Fixes   | #9418
| Tests pass?   | yes
| license?      | MIT

Commits
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887f71c [Form] fix CsrfProviderAdapter