@SuppressWarnings("unchecked")
    @Override
    public @NonNull <V> Optional<V> optional(final @NonNull String key) {
        return (Optional<V>) this.optional(CloudKey.of(key));
    }
Creates a new {@link SimpleMutableCloudKeyContainer}.

@param map backing map
cloud-core/src/main/java/org/incendo/cloud/key/SimpleMutableCloudKeyContainer.java