**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
self.logout()
        self.login()
        with conf_vars({('webserver', 'expose_config'): 'False'}):
            resp = self.client.get('configuration', follow_redirects=True)
        self.check_content_in_response(
            [
                'Airflow Configuration',
                '# Your Airflow administrator chose not to expose the configuration, '
                'most likely for security reasons.',
            ],
            resp,
        )
    def test_configuration_expose_config(self):
        self.logout()
        self.login()
        with conf_vars({('webserver', 'expose_config'): 'True'}):
            resp = self.client.get('configuration', follow_redirects=True)
        self.check_content_in_response(['Airflow Configuration', 'Running Configuration'], resp)
class TestRedocView(TestBase):
    def test_should_render_template(self):
        with self.capture_templates() as templates:
            resp = self.client.get('redoc')
            self.check_content_in_response('Redoc', resp)
        self.assertEqual(len(templates), 1)
        self.assertEqual(templates[0].name, 'airflow/redoc.html')
        self.assertEqual(
            templates[0].local_context,
            {'openapi_spec_url': '/api/v1/openapi.yaml'},
        )
class TestLogView(TestBase):