private void updatePath(String path) {
            requireNonNull(path, "path");
            checkArgument(this.path.charAt(0) == path.charAt(0),
                          "Not acceptable path for update: %s", path);
            this.path = path;
        }
Splits this {@link RoutingTrie.Node} into two by the given index of the path.
core/src/main/java/com/linecorp/armeria/server/RoutingTrieBuilder.java