**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
"""View to show records from Pool table"""
    route_base = '/pool'
    datamodel = AirflowModelView.CustomSQLAInterface(models.Pool)  
    class_permission_name = permissions.RESOURCE_POOL
    method_permission_name = {
        'add': 'create',
        'list': 'read',
        'edit': 'edit',
        'delete': 'delete',
        'action_muldelete': 'delete',
    }
    base_permissions = [
        permissions.ACTION_CAN_CREATE,
        permissions.ACTION_CAN_READ,
        permissions.ACTION_CAN_EDIT,
        permissions.ACTION_CAN_DELETE,
        permissions.ACTION_CAN_ACCESS_MENU,
    ]
    list_columns = ['pool', 'slots', 'running_slots', 'queued_slots']
    add_columns = ['pool', 'slots', 'description']
    edit_columns = ['pool', 'slots', 'description']
    base_order = ('pool', 'asc')
    @action('muldelete', 'Delete', 'Are you sure you want to delete selected records?', single=False)
    def action_muldelete(self, items):