Implements \Drupal\rest\LinkManager\RelationLinkManagerInterface::getRelationUri().
Overrides RelationLinkManagerInterface::getRelationUri
public function getRelationUri($entity_type, $bundle, $field_name) {
// @todo Make the base path configurable.
return url("rest/relation/{$entity_type}/{$bundle}/{$field_name}", array(
'absolute' => TRUE,
));
}