Gitlab::InternalEvents::EventDefinitions::InvalidMetricConfiguration: Unique property not defined for g_project_management_users_epic_issue_added_from_epic

Problem

g_project_management_users_epic_issue_added_from_epic is not properly configured [it's missing the unique: property] and therefore raises an error for Gitlab::InternalEvents::EventDefinitions::InvalidMetricConfiguration see https://sentry.gitlab.net/gitlab/gitlabcom/issues/4178012/?query=is%3Aunresolved%20InvalidMetricConfiguration

https://sentry.gitlab.net/gitlab/gitlabcom/issues/4178012/?referrer=gitlab_plugin

Gitlab::InternalEvents::EventDefinitions::InvalidMetricConfiguration: Unique property not defined for g_project_management_users_epic_issue_added_from_epic
  lib/gitlab/internal_events/event_definitions.rb:19:in `unique_property'
    raise(InvalidMetricConfiguration, "Unique property not defined for #{event_name}") unless unique_value
  lib/gitlab/internal_events.rb:15:in `track_event'
    unique_property = EventDefinitions.unique_property(event_name)
  lib/api/helpers.rb:706:in `track_event'
    Gitlab::InternalEvents.track_event(
  lib/api/usage_data.rb:78:in `block (2 levels) in <class:UsageData>'
    track_event(
  lib/api/api_guard.rb:219:in `call'
    response = super(env)
...
(159 additional frame(s) were not displayed)

Desired Outcome

Metric works correctly

Possible solution

Add correct event definition to the configuration