added a unit test

Author: juliuskoval

test/OpenTelemetry.Api.Tests/Logs/LogRecordDataTests.cs

@@ -102,6 +102,23 @@ record = default;
         Assert.Equal(now.ToUniversalTime(), record.Timestamp);
     }
 
+    [Fact]
+    public void ExceptionTest()
+    {
+        var record = new LogRecordData();
+        Assert.Null(record.Exception);
+
+        record = default;
+        Assert.Null(record.Exception);
+
+        var exception = new InvalidOperationException("test message");
+        record.Exception = exception;
+        Assert.Equal(exception, record.Exception);
+
+        record.Exception = null;
+        Assert.Null(record.Exception);
+    }
+
     [Fact]
     public void SetActivityContextTest()
     {