@Nullable
    private static String findVerb(String path, int begin) {
        for (int i = path.length() - 1; i >= begin; i--) {
            if (path.charAt(i) == ':') {
                return path.substring(i);
            }
        }
        return null;
    }
Returns the substring from the last colon ':' found after 'begin', including the colon.
Returns {@code null} if no colon is found after the 'begin' index.
core/src/main/java/com/linecorp/armeria/server/RoutingTrie.java