Added logic to detect a SystemPerformanceInformation JSON formatting error and fix it.

using System;

using System.IO;

using System.Runtime.Serialization.Json;

using System.Text.RegularExpressions;

using System.Threading.Tasks;

namespace Microsoft.Tools.WindowsDevicePortal

    /// </content>

    public partial class DevicePortal

    {

        /// <summary>

        /// The prefix for the <see cref="SystemPerformanceInformation" /> JSON formatting error.

        /// </summary>

        private static readonly string SysPerfInfoErrorPrefix = "{\"Reason\" : \"";

        /// <summary>

        /// The postfix for the <see cref="SystemPerformanceInformation" /> JSON formatting error.

        /// </summary>

        private static readonly string SysPerfInfoErrorPostfix = "\"}";

        /// <summary>

        /// Checks the JSON for any known formatting errors and fixes them.

        /// </summary>

        /// <typeparam name="T">Return type for the JSON message</typeparam>

        /// <param name="jsonStream">The stream that contains the JSON message to be checked.</param>

        private static void JsonFormatCheck<T>(Stream jsonStream)

        {

            if (typeof(T) == typeof(SystemPerformanceInformation))

            {

                StreamReader read = new StreamReader(jsonStream);

                string rawJsonString = read.ReadToEnd();

                // Recover from an error in which SystemPerformanceInformation is returned with an incorrect prefix, postfix and the message converted into JSON a second time.

                if (rawJsonString.StartsWith(SysPerfInfoErrorPrefix, StringComparison.InvariantCultureIgnoreCase) && rawJsonString.EndsWith(SysPerfInfoErrorPostfix, StringComparison.InvariantCultureIgnoreCase))

                {

                    // Remove the incorrect prefix and postfix from the JSON message.

                    rawJsonString = rawJsonString.Substring(SysPerfInfoErrorPrefix.Length, rawJsonString.Length - SysPerfInfoErrorPrefix.Length - SysPerfInfoErrorPostfix.Length);

                    // Undo the second JSON conversion.

                    rawJsonString = Regex.Replace(rawJsonString, "\\\\\"", "\"", RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);

                    rawJsonString = Regex.Replace(rawJsonString, "\\\\\\\\", "\\", RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);

                    // Overwrite the stream with the fixed JSON.

                    jsonStream.SetLength(0);

                    var sw = new StreamWriter(jsonStream);

                    sw.Write(rawJsonString);

                    sw.Flush();

                }

                jsonStream.Seek(0, SeekOrigin.Begin);

            }

        }

        /// <summary>

        /// Calls the specified API with the provided payload.

        /// </summary>

            {

                if (dataStream != null)

                {

                    JsonFormatCheck<T>(dataStream);

                    object response = serializer.ReadObject(dataStream);

                    data = (T)response;

                }