public List<String> getList(String k, List<String> defaultValue) {
    if (!containsKey(k))
      return defaultValue;

    String value = get(k);
    if (value.trim().isEmpty()) {
      return defaultValue;
    }
    String[] pieces = value.split("\\s*,\\s*");
    return Arrays.asList(pieces);
  }
Store and retrieve named, typed values as configuration for classes implementing this interface.
samza-api/src/main/java/org/apache/samza/config/Config.java