AssetApplication.js

addFieldsToPrepopList: function(){
        var mendatoryFields = this.editor.getAssetTabItem().getMainFields().append(this.editor.getAssetTabItem().getLocationFields());
        //filter optional fields to match the cookie
        var optionalFields = [];
        var optionalFieldsCookie = this.getOptionalFieldsCookieValues() || [];
        for (var i=0,field; field=this.editor.getAssetTabItem().getCustomFields()[i]; i++){
            if (optionalFieldsCookie.contains(field.getDWRField().getCode())){
                optionalFields.include(field);
            }
        }
        //combine all fields to be pre-populated
        var allFieldsToKeep = mendatoryFields.append(optionalFields);
        for (var i=0,field; field=allFieldsToKeep[i]; i++){
            console.log(field.getDWRField().getCode());
            this.addFieldToPrepopList(field);
        }
    },