protected function createPayload()
 {
     $payload = new SearchPayload();
     $payload->setQuery('foo bar');
     $refinement = new Refinement('TYPE', 'IMAGE');
     $payload->addRefinement($refinement);
     $refinement = new Refinement('where', 'france');
     $payload->addRefinement($refinement);
     $facet = new Facet('PROVIDER', 10, 20);
     $payload->addFacet($facet);
     $facet = new Facet('proxy_dc_coverage', 10, 20);
     $payload->addFacet($facet);
     $facet = new Facet('proxy_dc_contributor', 10, 20);
     $payload->addFacet($facet);
     return $payload;
 }