Post process for lazyload, mapping names to title and key

Question

the result for the post processing works for the following:

return o && { title: o.combndName, key: o.parentSqn, folder: true , lazy: true};

However, the data set for the child elements do not have title and key natively and also need to be mapped to those names.

How to create a post processing for lazy loaded child nodes?

function getTreeData() {
    $.getScript('//cdn.jsdelivr.net/npm/jquery.fancytree@2.27/dist/jquery.fancytree-all-deps.min.js', function () {
        $("#tree").fancytree({
            source: 
            {
                url: "/api/treetoplevel",
                data : {}
            },
            postProcess: function (event, data) { // activate lazy loading. 
                data.result = $.map(data.response, function (o) {
                    return o && { title: o.combndName, key: o.parentSqn, folder: true , lazy: true};//transform to tree output. TODO: play with columns after.  
                });
            },
            activate: function(event, data){
                var node = data.node;
                alert(node.key)
            },
            lazyLoad: function(event, data) {
                var node = data.node;
                data.result = { 
                  url: "/api/tree/" + node.key.toString(),
                  //url : "parent.json",
                  data: { mode: "children", parent: node.key },
                  cache: false
                };
             } 
          });
    });
};