13 files declare their use of RelationType in Relation 8

EntityCollector.php in relation_entity_collector/src/Form/EntityCollector.php

Contains \Drupal\relation_entity_collector\Form\EntityCollector.

relation.drush.inc in ./relation.drush.inc

Drush integration for the relation module.

relation.module in ./relation.module

Describes relations between entities.

relation.rules.inc in ./relation.rules.inc

Implements the Rules module API for Relation.

relation.views.inc in ./relation.views.inc

RelationAPITest.php in src/Tests/RelationAPITest.php

RelationGenerate.php in relation_devel/src/Form/RelationGenerate.php

Contains \Drupal\relation_devel\Form\RelationGenerate.

RelationTestBase.php in src/Tests/RelationTestBase.php

RelationUITest.php in src/Tests/RelationUITest.php

relation_dummy_field.module in relation_dummy_field/relation_dummy_field.module

A field storing arbitrary relations between entities.

relation_endpoint.module in relation_endpoint/relation_endpoint.module

Relation endpoints field.

relation_migrate.module in relation_migrate/relation_migrate.module

Migrations between *reference fields and relations.

relation_migrate.modules.inc in relation_migrate/relation_migrate.modules.inc

s Hook implementations in behalf of core and supported contrib modules.