public void test_immutableViaBeanBuilder() { LocalDate[] dates = {DATE_2010_01_01, DATE_2011_01_01, DATE_2012_01_01}; double[] values = {6, 5, 4}; BeanBuilder<? extends LocalDateDoubleTimeSeries> builder = SparseLocalDateDoubleTimeSeries.meta().builder(); builder.set("dates", dates); builder.set("values", values); LocalDateDoubleTimeSeries test = builder.build(); dates[0] = DATE_2012_01_01; values[0] = -1; LocalDateDoublePoint[] points = test.stream().toArray(LocalDateDoublePoint[]::new); assertEquals(points[0], LocalDateDoublePoint.of(DATE_2010_01_01, 6d)); assertEquals(points[1], LocalDateDoublePoint.of(DATE_2011_01_01, 5d)); assertEquals(points[2], LocalDateDoublePoint.of(DATE_2012_01_01, 4d)); }