javascript - Why does XHR Request To Azure Event Hub have improper message body? -

i sending ajax xhr message event hubs using javascript so...

    $.ajax({         type: "post",         url: eventhubconfig.servicebusuri + eventhubconfig.adhubname + "/messages/?timeout=60",         data: json.stringify(payload),         cache: false,         contenttype: "application/json",         beforesend: function(xhr) {             xhr.setrequestheader("authorization", sastoken);             xhr.setrequestheader("content-type", "application/json");         }     }); 

the payload simple object stringified json format like...

    var payload = {         platformid: 2,         articleid: 3,             ...             ...         type: "viewtype"     };  

the message when read event hub looks like..

occasionally receive message looks like...

please note these both body of message after getting utf8 string microsoft.servicebus.messaging.eventdata object in c# backend so...

    var jsonstring = encoding.utf8.getstring(eventdata.getbytes()); 

any ideas on how possible event hub receive second message?