Get the array of relation links.
Any field can be handled as a relation simply by changing how it is normalized. Therefore, there is no prior knowledge that can be used here to determine which fields to assign relation URIs. Instead, each field, even primitives, are given a relation URI. It is up to the caller to determine which URIs to use.
array An array of typed data ids (entity_type, bundle, and field name) keyed by corresponding relation URI.
public function getRelations() {
$cid = 'rest:links:relations';
$cache = $this->cache
->get($cid);
if (!$cache) {
$this
->writeCache();
$cache = $this->cache
->get($cid);
}
return $cache->data;
}