@Override
    public Class<? extends IPolicyFactory> getPolicyFactoryClass(IPluginRegistry pluginRegistry) {
        return loadConfigClass(GatewayConfigProperties.POLICY_FACTORY_CLASS, IPolicyFactory.class, pluginRegistry);
    }
@see io.apiman.gateway.engine.IEngineConfig#getPolicyFactoryClass(io.apiman.gateway.engine.IPluginRegistry)
gateway/platforms/war/src/main/java/io/apiman/gateway/platforms/war/WarEngineConfig.java