slice2cs bugs

Hi ZeroC team!

Recently I encountered two bugs in slice2cs compiler. Both of them lead to the compilation errors.

1) If I extend interface which has method with optional return value then generated code for child interface's Disp_ class has wrong signature: it returns just T instead of Ice.Optional<T>. Though other generated C# interfaces have correct signature.
For example:

	interface Printer {
		void printString(string s);
		optional (1) string getName();
	};

	interface Xerox extends Printer {
	};

generates that:

    public abstract class XeroxDisp_ : Ice.ObjectImpl, Xerox
    {
        #region Inherited Slice operations

        public string getName()
        {
            return getName(Ice.ObjectImpl.defaultCurrent);
        }

        public abstract string getName(Ice.Current current__);

2) If I use clr:serializable attribute to be able to use native C# struct then it works well unless I'm trying to use this struct as a return value. In the latter case slice2cs generates incorrect implementation of DelD_ class: in the beginning of the method it tries to assign null to the variable of the struct type. I was digging in generated code for a while and didn't see any specific reason to use null instead of default(T) here.
For example:

	["clr:serializable:System.DateTime"]
	sequence<byte> DateTime;

	interface Printer {
		DateTime getDateTime();
	};

generates that:

    public sealed class PrinterDelD_ : Ice.ObjectDelD_, PrinterDel_
    {
        [_System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1031")]
        public global::System.DateTime getDateTime(_System.Collections.Generic.Dictionary<string, string> context__, Ice.Instrumentation.InvocationObserver observer__)
        {
            Ice.Current current__ = new Ice.Current();
            initCurrent__(ref current__, "getDateTime", Ice.OperationMode.Normal, context__);
            global::System.DateTime result__ = null;

I hope that I provided clear explanations but if you need any additional assistance then don't hesitate to ask.
Thank you.