/// <summary>
/// Initializes a new instance of the <see cref="T:Xamarin.Cognitive.Speech.SpeechApiClient"/> class.
/// </summary>
/// <param name="subscriptionKey">A valid subscription key for the Speech API.</param>
/// <param name="speechRegion">The <see cref="SpeechRegion"/> where your speech service is deployed.</param>
/// <param name="authEndpoint">The endpoint used to get the authentication token for the Speech API. Defaults to <see cref="Endpoint.Authentication"/>. To use a custom auth endpoint, set this to an <see cref="Endpoint"/> with your endpoint details.</param>
/// <param name="speechEndpoint">The endpoint used to talk to the Speech API. Defaults to <see cref="Endpoint.SpeechServiceApi"/>. To use a CRIS/Custom Speech Service endpoint, set this to an <see cref="Endpoint"/> with the details for your CRIS service.</param>
public SpeechApiClient(string subscriptionKey, SpeechRegion speechRegion, Endpoint authEndpoint = null, Endpoint speechEndpoint = null)
{
this.subscriptionKey = subscriptionKey;
this.authEndpoint = authEndpoint ?? Endpoints.Authentication;
this.speechEndpoint = speechEndpoint ?? Endpoints.SpeechServiceApi;
this.SpeechRegion = speechRegion;
client = new HttpClient();
AuthClient = new AuthenticationClient(this.authEndpoint, this.subscriptionKey, this.SpeechRegion);
}