Connector with Attribute

[Jesse-Millwood]

I am trying to make a connector that has an attribute.
In the CAmkES manual it says:

Components and connectors can have extra data of an arbitrary
type associated with them. These are referred to as attributes. The
description of a component/connector must describe the name of the
attribute and its type. The value of the attribute itself is unspecified.
It is assigned when the entity is instantiated, and this assignment is
referred to as a setting. Attributes are generally used to specialise or
differentiate a component at runtime.

A sample connector that I am trying to make in my top level CAmkES app for a simple case is:

connector NewSharedData {
   from Dataport user_data template "seL4SharedData-from.template.c";
   to Dataport provider_data template "seL4SharedData-to.template.c";
   attribute string attr_string; 
}

When I build the repo I get Unexpected token 'attribute'. If I comment it out, all works fine because it is the same as the standard seL4SharedData connector.

I used the attribute keyword the same as when I make a component and it is fine.

Am I using this wrong or is it not supported anymore?

Setup:

• Host: Xubuntu 16.04
• CAmkES 2.3
• seL4 4.0