Arcgis JS API 3.x Popup infotemplate (popup) with relationship attributes

I’ve buildt a halfly harcoded popup builder widget, but i don’t know how to push fields from relationships into my popup div. I know how to do it in the ObjOriented way, but it’s not right for me.
Example:

   var popupTemplate = new PopupTemplate({
     "title": "Beverly Hills Trees By Block",
     "fieldInfos": [{
       "fieldName": "Point_Count",
       "label": "Count of Points",
       "format": {
         "places": 0,
         "digitSeparator": true
       }
     }, {
       "fieldName": "relationships/0/Point_Count_COMMON",
       "label": "Sum of species tree count",
       "format": {
         "places": 0,
         "digitSeparator": true
       },

I show my scructure: first function creates the popup content div, the second calls it, if i want popup.
But i couldnt find the documentation, how to get a graphic’s relationships, i can only get the attributes.
Any idea?

     function _getPopupTextContent(graphic) {  
       let popupContent = ""     
       popupContent += "<div style='padding:5px;background-color:rgb(251,183,46)'><b>" +
       "</b></div>" +
       "<table style='width:100%;'>"
       console.log(graphic)
       //popupContent +=  "<tr>"+graphic.attributes["relationships/1/FIELD"]+"</tr>" not working //undefined

       for (var property in graphic.attributes){
         console.log((property.toString()).split(/[.]/))
         var dbName = (property.toString()).split(/[.]/)[1]
         if (dbName !== undefined){
          var dbTableName = dbName.split(/[_]/)[3];    
         //console.log(maximoTableName)
         var fieldName = (property.toString()).split(/[.]/)[2];
         let value = graphic.attributes["DB.DB_ESRI_V_"+dbTableName+"_TT."+fieldName]
          
           if(fieldName == 'FIELDNAME1'&& value !== undefined){
             popupContent += "<tbody><tr><td id = 'attrtd'><b>Label</b></td><td id = 'attrtd''>" +
             value
           }
           if(fieldName == 'FIELDNAME2'&& value !== undefined){
             popupContent += "<tr><td id = 'attrtd'><b>Label</b></td><td id = 'attrtd''>" +
             value
           }
           if(fieldName == 'FIELDNAME3'){
             popupContent += "<tr><td id = 'attrtd'><b>Label</b></td><td id = 'attrtd''>" +
             value
           }
           if(fieldName == 'FIELDNAME4'&& value !== undefined){
             popupContent += "<tr><td id = 'attrtd'><b>Label</b></td><td id = 'attrtd''>" +
             value
           }
       }
           popupContent += "</td></tr>" +
                           "</td></tr>" +
                           "</a></td></tr>" +
                           "</tbody></table>"
       return popupContent;          
     }

     function _joinAndCreateInfoTemplate(){
       var mainLayer = _getWebmapOperationalLayerById(subStationLyrId);

       for(var title in popupSubIdDict){
         var popupName = _removeAccents(title).toLowerCase(); // subLayertitle
         var subId = popupSubIdDict[title]; //sub id

         mainLayer.getLayerObject().then(function (subLyrObj) {

           if (popupName == 'sublayer'){
             popupName = new InfoTemplate();
             popupName.setTitle(title);
             popupName.setContent(_getPopupTextContent);
           }

             subLyrObj.infoTemplates[subId] = {
               infoTemplate: new InfoTemplate(popupName)
             };