If you used the Visual Studio Code editor to edit, then copy and paste the codes to the Inline Editor and click on the Deploy button. Once deployed, do not forget to go into Default Welcome Intent and Default Fallback Intent and check Use webhook in the Fulfillment section. In Dialogflow, go to the Integrations section and click on Integration Settings, then click Test to go to the Google Assistant simulator.
The following screenshot shows the the result of testing the FortuneCookie agent with the basic webhook handling the Default Welcome Agent:
Test the Fortune Cookie Default Welcome Intent going through the webhook