At this point you need to choose: if you have already set up Email This Issue as a project, select it in the dropdown list. Otherwise, start creating new project by clicking Continue.
Creating a new project
If you choose to create a project because Email This Issue does not exist yet, you have to do the following:
Confirm that API is enabled. If you do it the first time, you’ll see this page. Click Go to Credentials.
Step 5 - Set up Credentials
When the followingscreen appears, make sure you configure it as it is in the screenshot. If completed, click What credentials do I need?
2. Set up Consent.
When the following screen appears, click Set up Consent Screen.
When the following screen appears, you can select Internal if you are connecting to an account in your organization (you use GSuite). If you are connecting to a regular Gmail account, select External.
3. Configure the consent for Email This Issue.
Note: A consent is a set of information that is presented during the authorization process. It helps identify the application that requires the authorization.
In the Consent page, enter the application name: "Email This Issue", and click Save.
4. Create credentials.
Go to Credentials in the left side menu. Click Create Credentials and select OAuth Client ID.
5. Configure your credentials.
Configure the credentials as shown in the following screenshot. The Application type is Web Application, and the name of the app is Email This Issue.
Important: Do not forget to add the Redirect URI. This is going to be specific to your Jira URL. The Redirect URI always follows this format: <JIRA BASE URL>/rest/jeti/1.0/oauth/callback
Click Create to receive the newly generated secure client credentials:
6. Save Client Credentials in Email This Issue.
Use the above screen to copy Your Client ID and Your Client Secret values into the Edit OAuth2 Client Credentials window under SETTINGS --> OAuth2 Client Credentials in Email This Issue as shown below: