Help with multiple returns in SOAP

Can anyone tell me how to push ActionWebService to create proper WSDL for multiple returns? My code looks like this:

class UserApi < ActionWebService::API::Base   api_method :getuserinfo,     :expects => [{:username => :string}, {:userpass => :string}],     :returns => [[{:firstname => :string}, {:lastname => :string}]] end

The WSDL doesn't include firstname and lastname names (only StringArray):

   <message name="Getuserinfo">       <part name="username" type="xsd:string"/>       <part name="userpass" type="xsd:string"/>    </message>    <message name="GetuserinfoResponse">       <part name="return" type="typens:StringArray"/>    </message>

And of course generates output:

        <return n2:arrayType="xsd:string[2]"             xmlns:n2="Error;             xsi:type="n2:Array">           <item>Tomasz</item>           <item>Tomczyk</item>         </return>

How can get into returns without having returns names in external soap client? Having WSDL like the one above I can only iterate throu items, which I think is not SOAP way.

Regards, Tomasz Tomczyk