+<?php
+
+namespace Drupal\entity_composite_relationship_test\Entity;
+
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+use Drupal\entity_reference_revisions\EntityNeedsSaveInterface;
+use Drupal\entity_reference_revisions\EntityNeedsSaveTrait;
+use Drupal\entity_test\Entity\EntityTestMulRev;
+
+/**
+ * Defines the test entity class.
+ *
+ * @ContentEntityType(
+ * id = "entity_test_composite",
+ * label = @Translation("Test entity - composite relationship"),
+ * base_table = "entity_test_composite",
+ * revision_table = "entity_test_composite_revision",
+ * data_table = "entity_test_composite_field_data",
+ * revision_data_table = "entity_test_composite_field_revision",
+ * translatable = TRUE,
+ * entity_revision_parent_type_field = "parent_type",
+ * entity_revision_parent_id_field = "parent_id",
+ * entity_revision_parent_field_name_field = "parent_field_name",
+ * admin_permission = "administer entity_test composite relationship",
+ * entity_keys = {
+ * "id" = "id",
+ * "uuid" = "uuid",
+ * "revision" = "revision_id",
+ * "bundle" = "type",
+ * "label" = "name",
+ * "langcode" = "langcode",
+ * }
+ * )
+ */
+class EntityTestCompositeRelationship extends EntityTestMulRev implements EntityNeedsSaveInterface {
+
+ use EntityNeedsSaveTrait;
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
+ $fields = parent::baseFieldDefinitions($entity_type);
+ $fields['parent_id'] = BaseFieldDefinition::create('string')
+ ->setLabel(t('Parent ID'))
+ ->setDescription(t('The ID of the parent entity of which this entity is referenced.'));
+
+ $fields['parent_type'] = BaseFieldDefinition::create('string')
+ ->setLabel(t('Parent type'))
+ ->setDescription(t('The entity parent type to which this entity is referenced.'));
+
+ $fields['parent_field_name'] = BaseFieldDefinition::create('string')
+ ->setLabel(t('Parent field name'))
+ ->setDescription(t('The entity parent field name to which this entity is referenced.'));
+
+ return $fields;
+ }
+
+}