**Description**
In the trigger page, there is a text area to enter (optional) conf json. It would be great if a sample JSON can be provided programatically while defining DAG

**Use case / motivation**

This will improve usability of the UI that triggers a DAG

airflow/www/views.py
if not task_instance:
                return None
            
            
            
            task_instance_data = [
                task_instance.state,
                task_instance.try_number,
                None,  
                None,  
            ]
            if task_instance.start_date:
                
                task_instance_data[2] = int(task_instance.start_date.timestamp())
                if task_instance.duration is not None:
                    task_instance_data[3] = int(task_instance.duration)
            return task_instance_data
        def recurse_nodes(task, visited):
            nonlocal node_count
            node_count += 1
            visited.add(task)
            task_id = task.task_id
            node = {
                'name': task.task_id,
                'instances': [encode_ti(task_instances.get((task_id, d))) for d in dates],
                'num_dep': len(task.downstream_list),
                'operator': task.task_type,
                'retries': task.retries,