Merge pull request #1245 from ouabing/avoid-empty-includes

Do not apply inclusions when model_includes is empty

Author: lgebhardt

lib/jsonapi/resource.rb

@@ -680,7 +680,7 @@ def apply_includes(records, options = {})
         include_directives = options[:include_directives]
         if include_directives
           model_includes = resolve_relationship_names_to_relations(self, include_directives.model_includes, options)
-          records = records.includes(model_includes)
+          records = records.includes(model_includes) if model_includes.present?
         end
 
         records