code: @Nonnull
  	public <N, UK> byte[] buildCompositeKeyNamesSpaceUserKey(
  		@Nonnull N namespace,
  		@Nonnull TypeSerializer<N> namespaceSerializer,
  		@Nonnull UK userKey,
  		@Nonnull TypeSerializer<UK> userKeySerializer) throws IOException {
  		serializeNamespace(namespace, namespaceSerializer);
  		userKeySerializer.serialize(userKey, keyOutView);
  		byte[] result = keyOutView.getCopyOfBuffer();
  		resetToKey();
  		return result;
  	}
docs: Returns a serialized composite key, from the key and key-group provided in a previous call to
  {@link #setKeyAndKeyGroup(Object, int)} and the given namespace, folloed by the given user-key.
  
  @param namespace           the namespace to concatenate for the serialized composite key bytes.
  @param namespaceSerializer the serializer to obtain the serialized form of the namespace.
  @param userKey             the user-key to concatenate for the serialized composite key, after the namespace.
  @param userKeySerializer   the serializer to obtain the serialized form of the user-key.
  @param <N>                 the type of the namespace.
  @param <UK>                the type of the user-key.
  @return the bytes for the serialized composite key of key-group, key, namespace.