The method getAllItems() throws Fatal error: Uncaught TypeError: Walmart\Apis\MP\MX\ItemsApi::getAllItemsWithHttpInfo(): Return value must be of type Walmart\Models\MP\MX\Items\ItemResponses
The response from WM is with all correct data but not in the correct or expected format, because the response is in XML and ItemsApi->getAllItemsWithHttpInfo() try to do a json_decode on the XML response string.
The method getAllItems() throws Fatal error: Uncaught TypeError: Walmart\Apis\MP\MX\ItemsApi::getAllItemsWithHttpInfo(): Return value must be of type Walmart\Models\MP\MX\Items\ItemResponses
The response from WM is with all correct data but not in the correct or expected format, because the response is in XML and ItemsApi->getAllItemsWithHttpInfo() try to do a json_decode on the XML response string.