Calling SAP BAPIs from Google Sheets

appscript.js

var endpoint ="https://callable-xxxxxxxxx-uc.a.run.app";
var user = "user1";
var password = "secret1";

function invokeRFC(rfcName,payload) {
  var options = {"method":"POST", "payload":payload, headers: {}};
  //check authentication data
  if(user.length>0){
    var auth = "Basic " + Utilities.base64Encode(user + ":" + password);
    options.headers['Authorization']=auth;
  }
  //call API
  var jsondata = UrlFetchApp.fetch(endpoint+"/rfc/"+rfcName, options);
  var obj   = JSON.parse(jsondata.getContentText());
  var rows=[];
  var header=[];
  //get list structure
  var names = Object.keys(obj);
  var listName ="";
  for(var col in names){
    if(names[col]!="RETURN"){
      listName=names[col];
    }
  }
  //get rows
  var list = obj[listName];
  for(var idx=0;idx<list.length;idx++){
    var entry = list[idx];
    var row=[];
    var cols=Object.keys(entry);
    for(var col in cols){
      header[col]=cols[col];
      row.push(entry[cols[col]]);
    }    
    rows.push(row);
  }
  rows.unshift(header);
  return rows;
}