A DESCRIPTION OF THE PROBLEM :
Execute the following unit test in JDK 1.8.0_172 and in JDK 10.0.1.

@Test
public void testCalendar() {
        TimeZone utc = TimeZone.getTimeZone("UTC");
        Locale en = Locale.forLanguageTag("en");
        int firstDayOfWeek = Calendar.getInstance(utc, en).getFirstDayOfWeek();
        Assert.assertEquals(1, firstDayOfWeek);

        TimeZone europeBerlin = TimeZone.getTimeZone("Europe/Berlin");
        Locale de = Locale.forLanguageTag("de");
        firstDayOfWeek = Calendar.getInstance(europeBerlin, de).getFirstDayOfWeek();
        Assert.assertEquals(2, firstDayOfWeek);
}

In JDK 1.8.0_172 the test passes. In JDK 10.0.1 it fails. In JDK 10 the getFirstDayOfWeek() method returns 1. Why?

REGRESSION : Last worked in version 8u172

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Execute the attached unit test in JDK 1.8.0_172 and in JDK 10.0.1.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
See assertions in attached unit test.

---------- BEGIN SOURCE ----------
@Test
    public void testCalendar() {
        TimeZone utc = TimeZone.getTimeZone("UTC");
        Locale en = Locale.forLanguageTag("en");
        int firstDayOfWeek = Calendar.getInstance(utc, en).getFirstDayOfWeek();
        Assert.assertEquals(1, firstDayOfWeek);

        TimeZone europeBerlin = TimeZone.getTimeZone("Europe/Berlin");
        Locale de = Locale.forLanguageTag("de");
        firstDayOfWeek = Calendar.getInstance(europeBerlin, de).getFirstDayOfWeek();
        Assert.assertEquals(2, firstDayOfWeek);
    }
---------- END SOURCE ----------

FREQUENCY : always