Whitelist language headers for AP.request
According to REST API docs:
The following request and response headers define important metadata for the Jira Cloud REST API resources.
X-Force-Accept-Language (request): controls how the standard HTTP Accept-Language header is processed. By default Accept-Language is ignored and the response is in the language configured in the user's profile or, when no language is configured for the user, the default Jira instance language. For the response to recognize Accept-Language send X-Force-Accept-Language = true as well. If Accept-Language requests a language that Jira can return the response is in that language, otherwise Jira returns the response in the default language. If Accept-Language is not specified the response is in the default language.
Therefore, both X-Force-Accept-Language=true and Accept-Language=en-US headers are needed when Apps want to take control of localization concerns.