feat: clear polymorphic lookup after initialize

Author: bf4

lib/jsonapi/resources/railtie.rb

@@ -18,6 +18,10 @@ class Railtie < ::Rails::Railtie
             ::JSONAPI::MimeTypes.parser.call(body)
           }
       end
+
+      initializer "jsonapi_resources.initialize", after: :initialize do
+        JSONAPI::Utils::PolymorphicTypesLookup.polymorphic_types_lookup_clear!
+      end
     end
   end
 end