AllNodes is not returning array with Telerik.Web.UI

[Sachita]

We have migrated to Telerik.Web.UI from Telerik.WebControls ,Telerik Version - 2021.3.914.45,.Net-4.8

Tried with get_allNodes() instead of AllNodes but no luck.

 function getNodes() {
				
				return this.getTree().AllNodes;                          //AllNodes is not returning Array

            }
 return {
                getTree: function() {
                    if (!this.elements["tree"]) { this.elements["tree"] = window[this.element.getAttribute("tree")]; }
                    return this.elements["tree"];
                },
                getHiddenFieldEl: function() {
                    if (!this.elements["hidden"]) { this.elements["hidden"] = $(this.element.getAttribute("hf")); }
                    return this.elements["hidden"];
                },
                toString: function() { return "Simple Tree"; },
                init: function() {
                    this.hasCheckBoxes = (this.element.getAttribute("checkmode") === "true");

                    Test.Controls.attachSubmitEvent(onSubmit, this, true);
                },
validate: function(source, args) {
                    var isValid = false;
                   var allNodes = getNodes.call(this);                                     //allNodes as Undefined
                    for(var i = 0, len = allNodes.length; i < len; i++) { 
					
                        var node = allNodes[i];
                        if(!node.Checked) { continue; }
                        
                        isValid = true;
                        break;
                    }
                    
                    args.IsValid = isValid;
                }

Can anyone please help to resolve this issue? what should be changed in the above code after migration?