Add labels support to IssueEvent returned via Webhook

[jkomyno]

Hi, thanks for this library.
I've noticed that even if the Label model is defined, it doesn't seem to be possible to retrieve the list of labels from an IssueEvent retrieved from GitLab's webhook API. Could it be added? Would you accept a PR with this feature?

[gmessner]

@jkomyno
The IssueEvent has had a few fields added recently with labels being one of them. We will add the missing fields to the event and include in the next release, which should be in the next few days.

For reference: https://docs.gitlab.com/ee/user/project/integrations/webhooks.html#issues-events

[jkomyno]

Thank you for the prompt response, I'm looking forward for the next release.

[gmessner]

@jkomyno
Support has been added for labels in the issue-event and is available in release 4.9.20. Please verify and close when you have a chance.

[gmessner]

@jkomyno
Since this feature is available in the latest release I am closing this issue, if you find any problems with the implementation, please feel free to re-open this issue.

[jkomyno]

What a timing! I have updated the library just 15 mins ago, so I finally have access to IssueEvent.getLabels(). I haven't run it yet but I'm confident that IssueEvent.getLabels() will never return null, right?

[gmessner]

If there is no label property in the event JSON it will return null, I cannot say whether that will ever be the case or not.