XLSX document uploading request

 Hi Guys , 

    We are giving the  document(content of the document) as a request to the POST API . When we trying to pass XLSX  extension document its throwing an error .

Appian is auto detecting the documents with reference media Type . But I cannot see an a template for XLSX.

  Can we send XLSX documents ? If not any work around to achieve ?

Many Thanks

Madhu