[Yaml] fixed some license headers
fixed CS for lambdas
fixed a typo
minor #9871 [Yaml] fixed some license headers (fabpot)

This PR was merged into the 2.3 branch.

Discussion
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[Yaml] fixed some license headers

| 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

Fixes lambdas once and for all.

Commits
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a2a6bd4 fixed a typo
35b407f fixed CS for lambdas
93edf44 [Yaml] fixed some license headers