All classes that implement ContactInterface in CRM Core 8
- class \Drupal\crm_core_contact\Entity\Individual extends \Drupal\entity\Revision\RevisionableContentEntityBase implements IndividualInterface uses EntityChangedTrait, EntityOwnerTrait
- class \Drupal\crm_core_contact\Entity\Organization extends \Drupal\entity\Revision\RevisionableContentEntityBase implements OrganizationInterface uses EntityChangedTrait, EntityOwnerTrait