code: @SuppressWarnings("unchecked")
    public static List<String> readStringListFromConfAsBase64(String key, Configuration conf) {
      String b64List = conf.get(key);
      if (b64List == null) {
        return null;
      }
  
      List<String> strings = Lists.newArrayList();
  
      for (String b64 : COMMA_SPLITTER.split(b64List)) {
        byte[] bytes = Base64.decodeBase64(b64.getBytes(Charsets.UTF_8));
        strings.add(new String(bytes, Charsets.UTF_8));
      }
  
      return strings;
    }
docs: Reads a list of strings stored as comma separated base64
  
  @param key for the configuration
  @param conf to read from
  @return the read list of strings, or null if key is not present in conf