/// <summary>
        /// Initializes a new instance of the <see cref="DeliveryClient"/> class for the unpublished content of the specified project.
        /// </summary>
        /// <param name="projectId">The identifier of the Kentico Cloud project.</param>
        /// <param name="previewApiKey">The Preview API key.</param>
        public DeliveryClient(string projectId, string previewApiKey)
        {
            if (projectId == null)
            {
                throw new ArgumentNullException(nameof(projectId), "Kentico Cloud project identifier is not specified.");
            }

            if (projectId == string.Empty)
            {
                throw new ArgumentException("Kentico Cloud project identifier is not specified.", nameof(projectId));
            }

            if (projectId.Length > PROJECT_ID_MAX_LENGTH)
            {
                throw new ArgumentException($"The specified Kentico cloud project identifier ({projectId}) is too long. Haven't you accidentally passed the Preview API key instead of the project identifier?", nameof(projectId));
            }

            if (previewApiKey == null)
            {
                throw new ArgumentNullException(nameof(projectId), "The Preview API key is not specified.");
            }

            if (previewApiKey == string.Empty)
            {
                throw new ArgumentException("The Preview API key is not specified.", nameof(projectId));
            }

            _urlBuilder = new DeliveryEndpointUrlBuilder(projectId, previewApiKey);
            _httpClient = new HttpClient();
            _httpClient.DefaultRequestHeaders.Add("Authorization", string.Format("Bearer {0}", previewApiKey));
        }
        /// <summary>
        /// Initializes a new instance of the <see cref="DeliveryClient"/> class for the published content of the specified project.
        /// </summary>
        /// <param name="projectId">The identifier of the Kentico Cloud project.</param>
        public DeliveryClient(string projectId)
        {
            if (projectId == null)
            {
                throw new ArgumentNullException(nameof(projectId), "Kentico Cloud project identifier is not specified.");
            }

            if (projectId == string.Empty)
            {
                throw new ArgumentException("Kentico Cloud project identifier is not specified.", nameof(projectId));
            }

            if (projectId.Length > PROJECT_ID_MAX_LENGTH)
            {
                throw new ArgumentException($"The specified Kentico cloud project identifier ({projectId}) is too long. Haven't you accidentally passed the Preview API key instead of the project identifier?", nameof(projectId));
            }

            _urlBuilder = new DeliveryEndpointUrlBuilder(projectId);
            _httpClient = new HttpClient();
        }