**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
"""Form widget used to display connection"""
    field_behaviours = json.dumps(ProvidersManager().field_behaviours)
class ConnectionModelView(AirflowModelView):
    """View to show records from Connections table"""
    route_base = '/connection'
    datamodel = AirflowModelView.CustomSQLAInterface(Connection)  
    class_permission_name = permissions.RESOURCE_CONNECTION
    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,
    ]
    extra_fields = list(ProvidersManager().connection_form_widgets.keys())
    list_columns = [
        'conn_id',
        'conn_type',