Angular TreeView JSON response

Question

I am new to Angular and i need your help !!!

I have a TreeView in my Angular project. i can generate TreeView from my API Response. My problem is I don't know how to send response back to my API with checked/unchecked values so I can save the response where I need it.

    applications_menu_tree: TreeviewItem[];

    ngOnInit(): void {
        this.getApplicationeMenuItems();
      }

    getApplicationeMenuItems() {
        this.appService.getPermissionsListTreeview('Application Menu')
          .pipe(first())
          .subscribe(
            response => this.application_menu_list = response
          );
      }

Here is the TreeView:

My problem is: How to take node values from Treeview and send to API as JSON ???