TODO: Interop Issue with WS-Trust Spec since it does not
specify the contents for AllowPostDating
<xs:element name="AllowPostdating" type="wst:AllowPostdatingType"/>
<xs:complexType name="AllowPostdatingType"/>
This indicates that returned tokens should allow requests for postdated
tokens.
TODO: The trust spec talks about RequestedAttachedReference,
RequestedUnAttachedReference (in section 6.2) and it talks
about <wst:RequestedTokenReference> in section 6.2.7.