public <T> T getObject(String key, String description, T defaultValue, Function<String, T> converter) {
    final String serializedValue = getArg(key);
    final T value = serializedValue == null ? defaultValue : converter.apply(serializedValue);
    logArgValue(key, description, value);
    return value;
  }
Returns an argument as long.

@throws NumberFormatException if the argument cannot be parsed as a long
planetiler-core/src/main/java/com/onthegomap/planetiler/config/Arguments.java