Minor candlestick json converter backwards compatility fix (#7428)

- Minor bug fix for candlestick json converter backwards compatibility,
  detected running the new report generator on an old lean backtest
  result json

Common/ChartPoint.cs

@@ -82,7 +82,7 @@ public decimal y
         /// Shortcut for <see cref="x"/> for C# naming conventions
         /// </summary>
         [JsonIgnore]
-        public decimal X => x;
+        public long X => x;
 
         /// <summary>
         /// Shortcut for <see cref="y"/> for C# naming conventions

Common/Util/CandlestickJsonConverter.cs

@@ -56,6 +56,15 @@ public override void WriteJson(JsonWriter writer, object value, JsonSerializer s
         /// </summary>
         public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
         {
+            if(reader.TokenType == JsonToken.StartObject)
+            {
+                // backwards compatibility with old format
+                var jObject = JObject.Load(reader);
+
+                var chartPoint = new ChartPoint(jObject["x"].Value<long>(), jObject["y"].Value<decimal>());
+                return new Candlestick(chartPoint.X, chartPoint.Y, chartPoint.Y, chartPoint.Y, chartPoint.Y);
+            }
+
             var jArray = JArray.Load(reader);
             return new Candlestick(jArray[0].Value<long>(), jArray[1].Value<decimal>(), jArray[2].Value<decimal>(),
                 jArray[3].Value<decimal>(), jArray[4].Value<decimal>());

Tests/Common/Util/CandlestickJsonConverterTests.cs

@@ -37,5 +37,21 @@ public void SerializeDeserializeReturnsSameValue()
             Assert.AreEqual(candlestick.Low, result.Low);
             Assert.AreEqual(candlestick.Close, result.Close);
         }
+
+        [Test]
+        public void BackwardsCompatility()
+        {
+            var dateTime = new DateTime(2023, 08, 01, 12, 11, 10);
+            var chartPoint = new ChartPoint(dateTime, 100);
+
+            var serializedChartPoint = JsonConvert.SerializeObject(chartPoint);
+            var result = (Candlestick)JsonConvert.DeserializeObject(serializedChartPoint, typeof(Candlestick));
+
+            Assert.AreEqual(chartPoint.Time, result.Time);
+            Assert.AreEqual(chartPoint.y, result.Open);
+            Assert.AreEqual(chartPoint.y, result.High);
+            Assert.AreEqual(chartPoint.y, result.Low);
+            Assert.AreEqual(chartPoint.y, result.Close);
+        }
     }
 }