**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
resp_html = resp.data.decode('utf-8')
        self.assertEqual(resp_code, resp.status_code)
        if isinstance(text, list):
            for line in text:
                self.assertIn(line, resp_html)
        else:
            self.assertIn(text, resp_html)
    def check_content_not_in_response(self, text, resp, resp_code=200):
        resp_html = resp.data.decode('utf-8')
        self.assertEqual(resp_code, resp.status_code)
        if isinstance(text, list):
            for line in text:
                self.assertNotIn(line, resp_html)
        else:
            self.assertNotIn(text, resp_html)
    @staticmethod
    def percent_encode(obj):
        return urllib.parse.quote_plus(str(obj))
    def create_user_and_login(self, username, role_name, perms):
        self.logout()
        fab_utils.create_user(
            self.app,
            username=username,
            role_name=role_name,
            permissions=perms,
        )
        self.login(username=username, password=username)
class TestConnectionModelView(TestBase):