**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

tests/www/test_views.py
return self.client.get('/logout/')
    @contextmanager
    def capture_templates(self) -> Generator[List[TemplateWithContext], None, None]:
        recorded = []
        def record(sender, template, context, **extra):  
            recorded.append(TemplateWithContext(template, context))
        template_rendered.connect(record, self.app)  
        try:
            yield recorded
        finally:
            template_rendered.disconnect(record, self.app)  
        assert recorded, "Failed to catch the templates"
    @classmethod
    def clear_table(cls, model):
        with create_session() as session:
            session.query(model).delete()
    def check_content_in_response(self, text, resp, resp_code=200):