feat:support nullable endpoint and responses endpoint

[Katerina-Charakhovich]

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ai-dial-actions]

Hey there and thank you for opening this pull request! 👋🏼

We require pull request titles to follow the Conventional Commits specification and it looks like your proposed title needs to be adjusted.

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No release type found in pull request title "feat:support nullable endpoint and responses endpoint". Add a prefix to indicate what kind of release this pull request corresponds to. For reference, see https://www.conventionalcommits.org/

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