@Override
    public <T> T getAttribute(String name, T defaultValue) {
        @SuppressWarnings("unchecked")
        T value = (T) conversation.get(name);
        if (value == null) {
            return defaultValue;
        } else {
            return value;
        }
    }
@see io.apiman.gateway.engine.policy.IPolicyContext#getAttribute(java.lang.String, java.lang.Object)
gateway/engine/core/src/main/java/io/apiman/gateway/engine/policy/PolicyContextImpl.java