docs: public static Sample of(final int length) {
  		if (length < 1) {
  			throw new IllegalArgumentException(format(
  				"Length must not be smaller than one, but was %d.", length
  			));
  		}
  
  		final double[] values = new double[length];
  		Arrays.fill(values, Double.NaN);
  		return of(values);
  	}