public static String implodeMultiline(List<String> lines) {
        if (lines==null) return null;
        return implode(lines.toArray(new String[0]), "\n");
    }
@Test
    public void testImplodeMultiline() {
        assertEquals(StringUtilities.implodeMultiline(List.of("foo", "bar")), "foo\nbar");
        assertEquals(StringUtilities.implodeMultiline(List.of("")), "");
        assertNull(StringUtilities.implodeMultiline(null));
        assertEquals(StringUtilities.implodeMultiline(List.of("\n")), "\n");
    }