[8.0.4xx] Fix serialization of TelemetryEventArgs data packets across MSBuild worker nodes

eng/Versions.props

@@ -2,7 +2,7 @@
 <!-- Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the MIT license. See License.txt in the project root for full license information. -->
 <Project>
   <PropertyGroup>
-    <VersionPrefix>17.11.3</VersionPrefix><DotNetFinalVersionKind>release</DotNetFinalVersionKind>
+    <VersionPrefix>17.11.4</VersionPrefix><DotNetFinalVersionKind>release</DotNetFinalVersionKind>
     <PackageValidationBaselineVersion>17.10.4</PackageValidationBaselineVersion>
     <AssemblyVersion>15.1.0.0</AssemblyVersion>
     <PreReleaseVersionLabel>preview</PreReleaseVersionLabel>

src/Build.UnitTests/BuildEventArgsSerialization_Tests.cs

@@ -873,6 +873,7 @@ public void PropertyInitialValueEventArgs()
                 e => e.HelpKeyword,
                 e => e.SenderName);
         }
+
         [Fact]
         public void ReadingCorruptedStreamThrows()
         {

src/Framework.UnitTests/CustomEventArgSerialization_Tests.cs

@@ -974,5 +974,62 @@ private static void VerifyTaskFinished(TaskFinishedEventArgs genericEvent, TaskF
             newGenericEvent.TaskFile.ShouldBe(genericEvent.TaskFile, StringCompareShould.IgnoreCase); // "Expected TaskFile to Match"
             newGenericEvent.TaskName.ShouldBe(genericEvent.TaskName, StringCompareShould.IgnoreCase); // "Expected TaskName to Match"
         }
+
+
+        [Fact]
+        public void TestTelemetryEventArgs()
+        {
+            // Test using reasonable values
+            TelemetryEventArgs genericEvent = new TelemetryEventArgs { EventName = "Good", Properties = new Dictionary<string, string> { { "Key", "Value" } } };
+            genericEvent.BuildEventContext = new BuildEventContext(5, 4, 3, 2);
+
+            // Serialize
+            genericEvent.WriteToStream(_writer);
+            long streamWriteEndPosition = _stream.Position;
+
+            // Deserialize and Verify
+            _stream.Position = 0;
+            TelemetryEventArgs newGenericEvent = new TelemetryEventArgs();
+            newGenericEvent.CreateFromStream(_reader, _eventArgVersion);
+            _stream.Position.ShouldBe(streamWriteEndPosition); // "Stream End Positions Should Match"
+            VerifyGenericEventArg(genericEvent, newGenericEvent);
+            VerifyTelemetryEvent(genericEvent, newGenericEvent);
+
+            // Test using null event name
+            _stream.Position = 0;
+            genericEvent = new TelemetryEventArgs { EventName = null, Properties = new Dictionary<string, string> { { "Key", "Value" } } };
+            // Serialize
+            genericEvent.WriteToStream(_writer);
+            streamWriteEndPosition = _stream.Position;
+
+            // Deserialize and Verify
+            _stream.Position = 0;
+            newGenericEvent = new TelemetryEventArgs();
+            newGenericEvent.CreateFromStream(_reader, _eventArgVersion);
+            _stream.Position.ShouldBe(streamWriteEndPosition); // "Stream End Positions Should Match"
+            VerifyGenericEventArg(genericEvent, newGenericEvent);
+            VerifyTelemetryEvent(genericEvent, newGenericEvent);
+
+            // Test using null property value name
+            _stream.Position = 0;
+            genericEvent = new TelemetryEventArgs { EventName = "Good", Properties = new Dictionary<string, string> { { "Key", null } } };
+            // Serialize
+            genericEvent.WriteToStream(_writer);
+            streamWriteEndPosition = _stream.Position;
+
+            // Deserialize and Verify
+            _stream.Position = 0;
+            newGenericEvent = new TelemetryEventArgs();
+            newGenericEvent.CreateFromStream(_reader, _eventArgVersion);
+            _stream.Position.ShouldBe(streamWriteEndPosition); // "Stream End Positions Should Match"
+            VerifyGenericEventArg(genericEvent, newGenericEvent);
+            VerifyTelemetryEvent(genericEvent, newGenericEvent);
+        }
+
+        private static void VerifyTelemetryEvent(TelemetryEventArgs expected, TelemetryEventArgs actual)
+        {
+            actual.EventName.ShouldBe(expected.EventName);
+            actual.Properties.ShouldBe(expected.Properties);
+        }
     }
 }

src/Framework/TelemetryEventArgs.cs

@@ -37,10 +37,9 @@ internal override void WriteToStream(BinaryWriter writer)
             foreach (var kvp in Properties)
             {
                 writer.Write(kvp.Key);
-                writer.Write(kvp.Value);
+                writer.WriteOptionalString(kvp.Value);
             }
         }
-
         internal override void CreateFromStream(BinaryReader reader, int version)
         {
             base.CreateFromStream(reader, version);
@@ -51,7 +50,7 @@ internal override void CreateFromStream(BinaryReader reader, int version)
             for (int i = 0; i < count; i++)
             {
                 string key = reader.ReadString();
-                string value = reader.ReadString();
+                string value = reader.ReadOptionalString();
                 Properties.Add(key, value);
             }
         }