public void addPolicyFactory(String name, PolicyFactory factory) {
        policies.put(name, factory);
    }
Registers a policy factory with this protocol under a given name. Whenever a policy is requested that matches
this name, the factory is invoked.

@param name    The name of the policy.
@param factory The policy factory.
messagebus/src/main/java/com/yahoo/messagebus/test/SimpleProtocol.java