I am using Spring and in my controller I have a `@ModelAttribute("params")'.

like this

@ModelAttribute("params")
public MultiValueMap<String, String> populateParams()
{


    final MultiValueMap<String, String> params = new LinkedMultiValueMap<>();

    params.add("signature", token.generate());
    params.add("params", token.generate());
    params.add("mockpayment", "true");
    params.add("req_reference_number", cartService.getSessionCart().getCode());
    params.add("reason_code", "100");
    return params;
}

this is used here in my ControllerA which is in charge to send it back to ControllerB using a POST, so in ControllerA I have a code like this :

@RequestMapping(value="/somePath", method =
{ RequestMethod.POST, RequestMethod.GET }))
public String test(final Model model, final RedirectAttributes redirectAttrs)
{       
    MultiValueMap<String, String> params = new LinkedMultiValueMap<>();


params = (MultiValueMap<String, String>) model.asMap().get("params");
...
}

What I want to do next is to send this Data structure Via a POST to ControllerB, how can I do that?