Delphi interface generic function - Is there a work around?

I have the following code

IProxy<T> = interface
  ['{1E3A98C5-78BA-4D65-A4BA-B6992B8B4783}']
  function Setup : ISetup<T>;
  function Proxy : T;
  function CastAs<I : IInterface> : IInterface;
end;

Is there a way to work around the compiler error that is received when compiling?

"[DCC Error] Delphi.Mocks.pas(123): E2535 Interface methods must not have parameterized methods"

Basically I would like to have this interface be passed around and be able to cast off it, by passing in the type to cast to and having that type returned. I can achieve this with a class, however would prefer passing around an interface.

Additional Info:

Say I have the following class

TInterfaceProxy<T> = class(TBaseProxy<T>)
private type
  TProxyVirtualInterface = class(TVirtualInterface)
  private
    FProxy : TInterfaceProxy<T>;
  protected
  public
    function QueryInterface(const IID: TGUID; out Obj): HRESULT; override; stdcall;
    constructor Create(AProxy : TInterfaceProxy<T>; AInterface: Pointer; InvokeEvent: TVirtualInterfaceInvokeEvent);
  end;
private
  FVirtualInterfaces : TDictionary<TGUID, TProxyVirtualInterface>;
protected
  function InternalQueryInterface(const IID: TGUID; out Obj): HRESULT; stdcall;
  function QueryInterface(const IID: TGUID; out Obj): HRESULT; override;
  function Proxy : T;override;
  function CastAs<I: IInterface> : I;
public
  constructor Create;override;
  destructor Destroy;override;
end;

CastAs works well here as the newly requested cast can be created a new virtual interface. Now if I want to pass this class around its fine. However if I require it as an interface i.e. TInterfaceProxy<T> = class(TBaseProxy<T>, IProxy<T>) it doesn't work understand that. Don't agree with it, but understand.

Therefore how do I get around this restriction so that I can call a C