There are several features that are now officially part of the GitHub REST API v3.
To use the affected API endpoints, you no longer need to pass preview headers. Before these previews graduated, you had to include preview headers as a custom media type in the
Accept header to use these endpoints.
To transfer a repository, you no longer need the Nightshade preview.
To invite users to an organization, you no longer need to use the Dazzler preview.
To access the Team Discussions API, you no longer need the Echo preview.
To use emoji in label names, add descriptions to labels or search for labels in a repository, you no longer need to use the Symmetra preview.
To retrieve someone's hovercard information in different contexts using the Hovercard API, you no longer need the Hagar preview.
To see nested teams in your responses or use the Nested Teams API, you no longer need the Hellcat preview.
Thanks again to everyone that tried out these API features during the preview period.