[Swift5] Add an async execute API to RequestBuilder<T>

[yosshi4486]

Add a new async API interface to RequestBuilder<T>. I changed APIs.mustache, then updated petstore samples by running ./bin/generate-samples.sh ./bin/configs/swift5*.

Issue: #14415

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Mentions

@4brunu

[4brunu]

Hi, could you please elaborate on the use case where you need this? Thanks

[4brunu]

Here we should have an @available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) before the function.

[yosshi4486]

I fixed it!

[yosshi4486]

Hi, could you please elaborate on the use case where you need this?

Ok @4brunu . I'd like to use the API in a situation where making a builder object is better than using high-level async API (like open class func usersIdTimeline(id: String) async throws -> Get2UsersIdTimelinesReverseChronologicalResponse)

An example of the usecase is computing onetime values and passing them into header fields, such as a signature or crypt things. I suppose using a builder instance and calling addHeaders method is better than setting onetime values into a global OpenAPIClientAPI.customHeaders property.

Currently, I can't find a way of passing the builder as a high-level API's parameter, or executing it with async/await.

My Concrete Usecase

I use openapi-gen swift5 client with an OAuth client library, like bellow:

let oauthClient = OAuthSwiftClient(
    consumerKey: "xxx",
    consumerSecret: "xxx",
    oauthToken: "xxx",
    oauthTokenSecret: "xxx",
    version: .oauth1
)

// Because oauth_signature needs a complete URL, I make a builder object in advance.
let tweetAPIRequestBuilder = TweetsAPI.usersIdTimelineWithRequestBuilder(id: "xxx")

// Get computed oauth authorization header fields
guard let computedHTTPHeaderFields = oauthClient.makeRequest(.init(url: URL(string: tweetAPIRequestBuilder.URLString)!)).config.urlRequest.allHTTPHeaderFields else {
    return
}

// Set onetime oauth values into the builder object's headers
tweetAPIRequestBuilder.addHeaders(computedHTTPHeaderFields)

// I can write like this, but...
// OpenAPIClientAPI.customHeaders = computedHTTPHeaderFields
// Task { let response = try? await TweetsAPI.usersIdTimeline(id: "xxx") }

// Call `try await builder.execute()` is simple
Task {
    do {
        let response = try await tweetAPIRequestBuilder.execute()
        let tweets = response.body.data
    } catch {
        print(error)
    }
}

[4brunu]

Thanks for explaining the use case.
Looks reasonable.
Could you please fix the issue that I open in code review?
That may help with the CI failure.
Thanks

[4brunu]

Looks good to me 👍
Thanks for creating this PR.

[yosshi4486]

Thank you for the code review!