public static List<String> getEffectivePaths(List<String> paths) {
        List<String> effectivePaths = new ArrayList<>();
        for (String path : paths) {
            if (!path.isEmpty()) {
                effectivePaths.add(path);
            }
        }
        if (effectivePaths.isEmpty()) {
            effectivePaths.add(".");
        }
        return effectivePaths;
    }
Convert a list of paths into the effective list of paths which should be used.
Empty strings will be removed.  If no paths are given, the current working
directory will be used.

@param paths     The input paths.  Non-null.

@return          The output paths.
shell/src/main/java/org/apache/kafka/shell/command/CommandUtils.java