///<summary>POST on /_transform/_preview <para>https://www.elastic.co/guide/en/elasticsearch/reference/current/preview-transform.html</para></summary>
///<param name = "body">The definition for the transform to preview</param>
///<param name = "requestParameters">Request specific configuration such as querystring parameters & request specific connection settings.</param>
public TResponse Preview <TResponse>(PostData body, PreviewTransformRequestParameters requestParameters = null)
where TResponse : class, ITransportResponse, new() => DoRequest <TResponse>(POST, "_transform/_preview", body, RequestParams(requestParameters));
public Task <TResponse> PreviewAsync <TResponse>(PostData body, PreviewTransformRequestParameters requestParameters = null, CancellationToken ctx = default)
where TResponse : class, ITransportResponse, new() => DoRequestAsync <TResponse>(POST, "_transform/_preview", ctx, body, RequestParams(requestParameters));
