Some of the java.time.chrono.Eras return empty display name for some styles and locales

Some of the java.time.chrono.Eras return empty display name for some styles and locales.
https://download.java.net/java/early_access/jdk14/docs/api/java.base/java/time/chrono/Era.html#getDisplayName(java.time.format.TextStyle,java.util.Locale)
Specification:
"Gets the textual representation of this era. This returns the textual name used to identify the era, suitable for presentation to the user. The parameters control the style of the returned text and the locale. If no textual mapping is found then the numeric value is returned."

Consider the following code sample iterating over eras, text styles and avail locales:

import java.time.chrono.*;
import java.time.format.TextStyle;
import java.util.*;

public class GetDisplayNameEmpty {
    public static void main(String[] args) {
        List<Era> erasList = new ArrayList<>();
        erasList.addAll(Arrays.asList(JapaneseEra.values()));
        erasList.addAll(Arrays.asList(HijrahEra.values()));
        erasList.addAll(Arrays.asList(IsoEra.values()));
        erasList.addAll(Arrays.asList(ThaiBuddhistEra.values()));
        erasList.addAll(Arrays.asList(MinguoEra.values()));
        int nonEmptyCases = 0;
        int emptyCases = 0;
        for (Era era : erasList) {
            for (TextStyle style : TextStyle.values()) {
                for (Locale locale : Locale.getAvailableLocales()) {
                    String displayName = era.getDisplayName(style, locale);
                    if (displayName.isEmpty()) {
                        System.out.println("era.getDisplayName(style, locale) is empty for era = " + era + ", style = " + style + ", locale = " + locale);
                        emptyCases++;
                    } else {
                        nonEmptyCases++;
                    }
                }
            }
        }
        System.out.println("Non empty: " + nonEmptyCases + ", empty: " + emptyCases);
    }
}

It would print out something like:

era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = el
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = fa
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = uk
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = el
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = uk
era.getDisplayName(style, locale) is empty for era = Meiji, style = FULL_STANDALONE, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = el
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = fa
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = uk
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = el
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = uk
era.getDisplayName(style, locale) is empty for era = Meiji, style = SHORT_STANDALONE, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Meiji, style = NARROW, locale = fa
era.getDisplayName(style, locale) is empty for era = Meiji, style = NARROW, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Meiji, style = NARROW, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Meiji, style = NARROW_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Meiji, style = NARROW_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Meiji, style = NARROW_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = el
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = fa
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = uk
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = el
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = uk
era.getDisplayName(style, locale) is empty for era = Taisho, style = FULL_STANDALONE, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = el
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = fa
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = uk
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = el
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = uk
era.getDisplayName(style, locale) is empty for era = Taisho, style = SHORT_STANDALONE, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Taisho, style = NARROW, locale = fa
era.getDisplayName(style, locale) is empty for era = Taisho, style = NARROW, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Taisho, style = NARROW, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Taisho, style = NARROW_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Taisho, style = NARROW_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Taisho, style = NARROW_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = el
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = fa
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = uk
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = el
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = uk
era.getDisplayName(style, locale) is empty for era = Showa, style = FULL_STANDALONE, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = el
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = fa
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = uk
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = el
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = el_CY
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = uk_UA
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = uk
era.getDisplayName(style, locale) is empty for era = Showa, style = SHORT_STANDALONE, locale = el_GR
era.getDisplayName(style, locale) is empty for era = Showa, style = NARROW, locale = fa
era.getDisplayName(style, locale) is empty for era = Showa, style = NARROW, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Showa, style = NARROW, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = Showa, style = NARROW_STANDALONE, locale = fa
era.getDisplayName(style, locale) is empty for era = Showa, style = NARROW_STANDALONE, locale = fa_AF
era.getDisplayName(style, locale) is empty for era = Showa, style = NARROW_STANDALONE, locale = fa_IR
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW, locale = nb_SJ
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW, locale = no
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW, locale = nb_NO
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW, locale = no_NO
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW, locale = nb
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW_STANDALONE, locale = nb_SJ
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW_STANDALONE, locale = no
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW_STANDALONE, locale = nb_NO
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW_STANDALONE, locale = no_NO
era.getDisplayName(style, locale) is empty for era = BEFORE_ROC, style = NARROW_STANDALONE, locale = nb
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = in
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = lo
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = vi_VN
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = lo_LA
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = in_ID
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = ja_JP_JP_#u-ca-japanese
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = ja_JP
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = ja
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL, locale = vi
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = in
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = lo
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = vi_VN
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = lo_LA
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = in_ID
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = ja_JP_JP_#u-ca-japanese
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = ja_JP
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = ja
era.getDisplayName(style, locale) is empty for era = ROC, style = FULL_STANDALONE, locale = vi
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT, locale = in
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT, locale = lo
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT, locale = vi_VN
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT, locale = lo_LA
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT, locale = in_ID
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT, locale = vi
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT_STANDALONE, locale = in
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT_STANDALONE, locale = lo
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT_STANDALONE, locale = vi_VN
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT_STANDALONE, locale = lo_LA
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT_STANDALONE, locale = in_ID
era.getDisplayName(style, locale) is empty for era = ROC, style = SHORT_STANDALONE, locale = vi
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW, locale = in
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW, locale = lo
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW, locale = vi_VN
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW, locale = lo_LA
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW, locale = in_ID
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW, locale = vi
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW_STANDALONE, locale = in
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW_STANDALONE, locale = lo
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW_STANDALONE, locale = vi_VN
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW_STANDALONE, locale = lo_LA
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW_STANDALONE, locale = in_ID
era.getDisplayName(style, locale) is empty for era = ROC, style = NARROW_STANDALONE, locale = vi
Non empty: 55490, empty: 166