.net - Utilize Optional Parameters In Delegates?

However, I am wondering if there are any workarounds or plans for incorporating this feature into VB.NET in the future?What I'd like to do:

Public Delegate Function Deserializer(Of T)(ByRef Buffer() As Byte, optional ByRef BufferPosition As Integer = 0) As T
'Implementation of a func that matches the delegate'
Class A
Public Function Deserialize(Byref Buffer() as Byte, optional Byref BufferPosition as integer = 0)
....

In the absence of specifying "optional" inside the actual delegate itself, it'd at least be nice to be able to do it in the function implementation only:

Public Delegate Function Deserializer(Of T)(ByRef Buffer() As Byte, ByRef BufferPosition As Integer) As T
'Implementation of a func that matches the delegate'
Class A
Public Function Deserialize(Byref Buffer() as Byte, optional Byref BufferPosition as integer = 0)
....

At least this second way, the functions for the delegate will always have a value mapped to each parameter, although some may come from the function side and not the calling side.