public protocol TransferDetails: Sendable {
    var transferId: String { get }
}

struct CreateTransferResponse: TransferDetails {
    var transferId: String
}

if let url = URL(string: "https://example.com/v1/verifyFundsAndCreateTransfer") {
    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "POST"
    // transferRequest is passed from the SDK to the host
    urlRequest.httpBody = try JSONEncoder().encode(transferRequest)
    if let (data, _) = try? await URLSession.shared.data(for: urlRequest),
       let transferDetails: TransferDetails? = try? JSONDecoder().decode(CreateTransferResponse.self, from: data) {
        ...
    }
}