Gravity Forms Slack Add-On was updated to version 1.6, from version 1.5. Changelog:

• Added “gform_slack_invite” filter for modifying invite user parameters.
• Added support for auto-inviting to specific channels when inviting users to team.
• Added support for mapping first and last name when inviting users to team.
• Fixed strings for translations.
• Fixed an issue with the request failed message when a WP_Error occurs.