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

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