chore: import upstream snapshot with attribution

Common/Util/SecurityIdentifierJsonConverter.cs

@@ -0,0 +1,47 @@
+/*
+ * QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
+ * Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); 
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+*/
+
+using Newtonsoft.Json;
+using QuantConnect.Securities;
+
+namespace QuantConnect.Util
+{
+    /// <summary>
+    /// A <see cref="JsonConverter"/> implementation that serializes a <see cref="SecurityIdentifier"/> as a string
+    /// </summary>
+    public class SecurityIdentifierJsonConverter : TypeChangeJsonConverter<SecurityIdentifier, string>
+    {
+        /// <summary>
+        /// Converts as security identifier to a string
+        /// </summary>
+        /// <param name="value">The input value to be converted before serialziation</param>
+        /// <returns>A new instance of TResult that is to be serialzied</returns>
+        protected override string Convert(SecurityIdentifier value)
+        {
+            return value.ToString();
+        }
+
+        /// <summary>
+        /// Converts the input string to a security identifier
+        /// </summary>
+        /// <param name="value">The deserialized value that needs to be converted to T</param>
+        /// <returns>The converted value</returns>
+        protected override SecurityIdentifier Convert(string value)
+        {
+            return SecurityIdentifier.Parse(value);
+        }
+    }
+}