**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
edges_to_add.add((task_group.downstream_join_id, target_id))
            for child in task_group.get_leaves():
                edges_to_add.add((child.task_id, task_group.downstream_join_id))
                edges_to_skip.add((child.task_id, target_id))
        
        
        
        for source_id in task_group.upstream_task_ids:
            edges_to_add.add((source_id, task_group.upstream_join_id))
            for child in task_group.get_roots():
                edges_to_add.add((task_group.upstream_join_id, child.task_id))
                edges_to_skip.add((source_id, child.task_id))
        for child in task_group.children.values():
            collect_edges(child)
    collect_edges(dag.task_group)
    
    edges = set()
    def get_downstream(task):
        for child in task.downstream_list:
            edge = (task.task_id, child.task_id)
            if edge not in edges:
                edges.add(edge)
                get_downstream(child)
    for root in dag.roots:
        get_downstream(root)
    return [
        {'source_id': source_id, 'target_id': target_id}
        for source_id, target_id in sorted(edges.union(edges_to_add) - edges_to_skip)
    ]
def circles(error):