public void UpdateClientCommand_Executed(object sender)
{
_contoData.ClientUpdate(new Client
{
Id = ExistingId,
Name = ExistingName,
Address = ExistingAddress,
City = ExistingCity,
PostalCode = ExistingPostalCode,
FiscalCode = ExistingFiscalCode,
VatCode = ExistingVatCode
});
_completeList = new List <Client>(_contoData.ClientsGet());
SetClientsList();
UpdatePanelVisibility = Visibility.Collapsed;
}