@Override
                public T getOrDefault() {
                    return current.orElse(defaultSupplier.get());
                }
Register an action that will refresh the cached value for key. Uses the current value as a reference and will
update from the dynamic property source to either delete or set a new value.

@param key - Property key without client name or namespace
ribbon-core/src/main/java/com/netflix/client/config/ReloadableClientConfig.java