data (UploadRawData | UploadFile)[] - The post data to be sent to the
new window.contentType string - The content-type header used for the data. One of
application/x-www-form-urlencoded or multipart/form-data. Corresponds to
the enctype attribute of the submitted HTML form.boundary string (optional) - The boundary used to separate multiple parts of
the message. Only valid when contentType is multipart/form-data.