TableDataUtils { public static List<String> normalizeColumns(List<Object> columns) { return columns.stream() .map(TableDataUtils::normalizeColumn) .collect(Collectors.toList()); }  static String normalizeColumn(String column); static String normalizeColumn(Object obj); static List<String> normalizeColumns(List<Object> columns); static List<String> normalizeColumns(Object[] columns);  }
@Test public void testColumns() { assertEquals(Lists.newArrayList("hello world", "hello world"), TableDataUtils.normalizeColumns(new Object[]{"hello\tworld", "hello\nworld"})); assertEquals(Lists.newArrayList("hello world", "null"), TableDataUtils.normalizeColumns(new String[]{"hello\tworld", null})); }