KeyName as default value for ownerKey;

Author: hans-thomas

src/Eloquent/HybridRelations.php

@@ -212,6 +212,10 @@ public function morphTo($name = null, $type = null, $id = null, $ownerKey = null
 
         [$type, $id] = $this->getMorphs(Str::snake($name), $type, $id);
 
+        if ($ownerKey === null){
+            $ownerKey = $this->getKeyName();
+        }
+
         // If the type value is null it is probably safe to assume we're eager loading
         // the relationship. When that is the case we will pass in a dummy query as
         // there are multiple types in the morph and we can't use single queries.