test.vb

Imports System.Collections.ObjectModel

Module Module1

    Sub Main()
        Dim c As New Collection(Of Integer) From {1}
        Foo(Of Integer)(c)
    End Sub

    Sub Foo(Of T)(ByVal o As Object)
        Dim c = CType(o, Collection(Of T))
        Console.WriteLine(c.FirstOrDefault())
    End Sub

End Module