code: static final void checkSplitPointsOrder(final double[] values) {
      if (values == null) {
        throw new SketchesArgumentException("Values cannot be null.");
      }
      final int lenM1 = values.length - 1;
      for (int j = 0; j < lenM1; j++) {
        if (values[j] < values[j + 1]) { continue; }
        throw new SketchesArgumentException(
            "Values must be unique, monotonically increasing and not NaN.");
      }
    }
docs: Checks the sequential validity of the given array of double values.
  They must be unique, monotonically increasing and not NaN.
  @param values the given array of double values