我可以用一个扩展方法来表示VB.NET?

我想知道是否可以使用DataContractJsonSerializer序列化结构类型,或者它必须是引用/类类型?

<Extension()> Public Function ToJSON(ByVal target As Object) As String
    Dim serializer = New System.Runtime.Serialization.Json.DataContractJsonSerializer(target.GetType)
    Using ms As MemoryStream = New MemoryStream()
        serializer.WriteObject(ms, target)
        ms.Flush()

        Dim bytes As Byte() = ms.GetBuffer()

        Dim json As String = Encoding.UTF8.GetString(bytes, 0, bytes.Length).Trim(Chr(0))

        Return json
    End Using
End Function

但是,如果我在一个结构类型上调用它,比如KeyValuePair(T1,T2),我会得到以下错误: