DocStarDownloadFile via REST SSO

@daveleland, sorry had to dig around, but I found it.
Take my notes from the snippet before about ‘epicorUrl’ and ‘authentication’.

function downloadAttachment() {
    console.log("contentObject2: ", contentObject2);
    let epicorUrl = '';
    let authentication = '';
    let url = '/v1/Ice.BO.AttachmentSvc/DocStarDownloadFile';

    var val = contentObject2.value[0];
    var refNum = val.XFileRefNum;
    var xRefNum = parseInt(refNum);
    //const response2 = JSON.parse(contentObject2);
    return (async () => {
        const rawResponse3 = await fetch(epicorUrl + url, {
          method: 'POST',
          headers: {
            "accept": "application/json",
            "Content-Type": "application/json",
            "Authorization": authuentication
          },
          body: JSON.stringify({
            xFileRefNum: xRefNum,
            metadata: {
            }
          })
        });
        const content3 = await rawResponse3.json();

        //console.log(content3);
        contentObject3 = content3;
    })();
};

I think it gives you a base64 string, and you’ll have to convert it to whatever file format it should be.