TESTCASE DESCRIPTION:
--- FirstYearTest.java -------------
import java.time.chrono.JapaneseChronology;
import java.time.chrono.JapaneseDate;
import java.time.format.DateTimeFormatter;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Locale;

public class FirstYearTest{
    static Locale jplocale;

    public static void main(String[] args){
        jplocale = new Locale("ja", "JP", "JP");
        String str;
        String pattern = "GGGGyyyy\u5e74";

        System.out.println("--- Calendar SimpleDateFormst ---");
        Calendar cal = Calendar.getInstance();
        cal.set(1989,0,8); // = Heisei 1

        SimpleDateFormat format = new SimpleDateFormat(pattern, jplocale);
        str = format.format(cal.getTime());
        System.out.println("\""+pattern+"\" "+str);

        System.out.println("--- JapaneseDate DateTimeFormatter ---");
        printDateTimeFormatter("GGGGyyyy\u5e74");
        System.out.println("--- JapaneseDate DateTimeFormatter trials ---");
        printDateTimeFormatter("GGGGyyy\u5e74");
        printDateTimeFormatter("GGGGyy\u5e74");
        printDateTimeFormatter("GGGGy\u5e74");
    }

    static void printDateTimeFormatter(String pattern) {
        JapaneseDate date = JapaneseDate.of(1989,1,8);
        String str = date.format(DateTimeFormatter.ofPattern(pattern)
                            .withLocale(jplocale));
        System.out.println("\""+pattern+"\" "+str);
    }
}

FALING OUTPUT:
--- Calendar SimpleDateFormst ---
"GGGGyyyy\u5e74" \u5e73\u6210\u5143\u5e74
--- JapaneseDate DateTimeFormatter ---
"GGGGyyyy\u5e74" \u5e73\u62100001\u5e74


Expected Result:
--- Calendar SimpleDateFormst ---
"GGGGyyyy\u5e74" \u5e73\u6210\u5143\u5e74
--- JapaneseDate DateTimeFormatter ---
"GGGGyyyy\u5e74" \u5e73\u6210\u5143\u5e74