Returns an Iterator (of Element) with the target entity's items or null if none. Each Element
must include a JID attribute and may include the name and node attributes of the entity. In
case that the sender of the disco request is not authorized to discover items an
UnauthorizedException will be thrown.
name - the recipient JID's name.
senderJID - the XMPPAddress of user that sent the disco items request.
an Iterator (of Element) with the target entity's items or null if none.