**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.pool['pool'] = ''
        resp = self.client.post('/pool/add', data=self.pool, follow_redirects=True)
        self.check_content_in_response('This field is required.', resp)
    def test_odd_name(self):
        self.pool['pool'] = 'test-pool<script></script>'
        self.session.add(models.Pool(**self.pool))
        self.session.commit()
        resp = self.client.get('/pool/list/')
        self.check_content_in_response('test-pool&lt;script&gt;', resp)
        self.check_content_not_in_response('test-pool<script>', resp)
    def test_list(self):
        self.pool['pool'] = 'test-pool'
        self.session.add(models.Pool(**self.pool))
        self.session.commit()
        resp = self.client.get('/pool/list/')
        
        with self.app.test_request_context():
            url = url_for('TaskInstanceModelView.list', _flt_3_pool='test-pool', _flt_3_state='running')
            used_tag = Markup("<a href='{url}'>{slots}</a>").format(url=url, slots=0)
            url = url_for('TaskInstanceModelView.list', _flt_3_pool='test-pool', _flt_3_state='queued')
            queued_tag = Markup("<a href='{url}'>{slots}</a>").format(url=url, slots=0)
        self.check_content_in_response(used_tag, resp)
        self.check_content_in_response(queued_tag, resp)
class TestMountPoint(unittest.TestCase):
    @classmethod
    @conf_vars({("webserver", "base_url"): "http://localhost/test"})
    def setUpClass(cls):