URL edits in webhook notifcations are adding extra special characters

Issue Summary

This is reproducible on Data Center: yes

This issue is reproducible on Server:yes

When creating a notification for plan if we select a webhook notification if we edit the windows (webhook build notification, for example) and write this: http://example&something, when we save and open again the edition you can see the url is changed to http://example&something.

Steps to Reproduce

1. Create a plan, configure notifications for a plan
2. Select Recipient Type as Webhooks
3. Enter url as :- http://example&something and save it
4. Edit the url and you will see a & introduced to the url 
5. Now if you save the setting the url appears as http://example&something

Expected Results

Url should not introduce special characters like amp;

Actual Results

Looks like the webhook notification is appending an extra amp to the & url.

The main issue for this case is the change of & to &amp and if we try to resave again it  will add more ;amp and more ;amp ….. adding into the chainIf we remove the amp; or amp;amp;amp;…. leaving only the & and save, everything will works.The problem occurs when you open the windows to change anything.

Workaround

A work around for this issue would be edit the below file and remove the ?html from the ${webhookUrl}::-

<bamboo-install>/atlassian-bamboo/templates/plugins/notifications/webhookRecipientEdit.ftl

From :

[@s.textfield key='config.webhook.selectwebhook.url' value='${webhookUrl?html}' name='webhookUrl' /]

should be :

[@s.textfield key='config.webhook.selectwebhook.url' value='${webhookUrl}' name='webhookUrl' /]

Then restart Bamboo.