This Composer plugin will display a warning when users install or update Drupal packages that are not supported by the Drupal Security team, as per the Security Advisory Policy.

Installing or updating a "non-covered" Drupal package will display:

You are using Drupal packages that are not supported by the Drupal Security Team!
  - drupal/consumers:1.0.0.0-beta1: Project has not opted into security advisory coverage!
  - drupal/inline_entity_form:1.0.0.0-beta1: Beta releases are not covered by Drupal security advisories.
  - drupal/scheduled_updates:1.0.0.0-alpha6: Project has not opted into security advisory coverage!
  - drupal/diff:1.0.0.0-RC1: RC releases are not covered by Drupal security advisories.
  - drupal/seckit:1.0.0.0-alpha2: Alpha releases are not covered by Drupal security advisories.
  - drupal/security_review:dev-1.x: Dev releases are not covered by Drupal security advisories.
See https://www.drupal.org/security-advisory-policy for more information.