如何使Zend Soap Server自动发现基本的xsd类型？

I am working on the Zend-framework-based Soap server, using AutoDiscovery to create wsdl file. It works all right for the either basic integers and strings or complex types based on these two primitives. However, I am unable to define my variables as date type

Here is an example data file

<?php
namespace Soap;
class Data_Object_Period
{
    /** @var string */
    public $EndDate;
}

if I make it string, it in a wsdl file it looks like

<xsd:element name="EndDate" type="xsd:string" nillable="true"/>

But if I make it date, I get an error

Cannot add a complex type date that is not an object or where class could not be found in "DefaultComplexType" strategy.

How can I add standard xsd date type to AutoDiscover strategy?

You didn't specify the ZF version you're using, but I believe the answer should be the same. The WSDL Auto Discovery doesn't support date types, as you can see here:

http://framework.zend.com/manual/1.12/en/zend.soap.autodiscovery.html

Scroll down to Autodiscovering Datatypes. I suggest you keep on using it as string and then verify if it is a valid date in the function.