src/java.base/share/classes/sun/util/locale/provider/CalendarNameProviderImpl.java

*** 61,70 ****
--- 61,78 ----
          String name = null;
          String key = getResourceKey(calendarType, field, style, javatime);
          if (key != null) {
              LocaleResources lr = LocaleProviderAdapter.forType(type).getLocaleResources(locale);
              String[] strings = javatime ? lr.getJavaTimeNames(key) : lr.getCalendarNames(key);
+ 
+             // If standalone names are requested and no "standalone." resources are found,
+             // try the default ones instead.
+             if (strings == null && key.indexOf("standalone.") != -1) {
+                 key = key.replaceFirst("standalone.", "");
+                 strings = javatime ? lr.getJavaTimeNames(key) : lr.getCalendarNames(key);
+             }
+ 
              if (strings != null && strings.length > 0) {
                  if (field == DAY_OF_WEEK || field == YEAR) {
                      --value;
                  }
                  if (value < 0 || value >= strings.length) {
*** 116,125 ****
--- 124,141 ----
          String key = getResourceKey(calendarType, field, style, javatime);
          Map<String, Integer> map = new TreeMap<>(LengthBasedComparator.INSTANCE);
          if (key != null) {
              LocaleResources lr = LocaleProviderAdapter.forType(type).getLocaleResources(locale);
              String[] strings = javatime ? lr.getJavaTimeNames(key) : lr.getCalendarNames(key);
+ 
+             // If standalone names are requested and no "standalone." resources are found,
+             // try the default ones instead.
+             if (strings == null && key.indexOf("standalone.") != -1) {
+                 key = key.replaceFirst("standalone.", "");
+                 strings = javatime ? lr.getJavaTimeNames(key) : lr.getCalendarNames(key);
+             }
+ 
              if (strings != null) {
                  if (!hasDuplicates(strings)) {
                      if (field == YEAR) {
                          if (strings.length > 0) {
                              map.put(strings[0], 1);
*** 279,290 ****
              }
              key.append("Month").append(toStyleName(baseStyle));
              break;
  
          case DAY_OF_WEEK:
!             // support standalone narrow day names
!             if (isStandalone && isNarrow) {
                  key.append("standalone.");
              }
              key.append("Day").append(toStyleName(baseStyle));
              break;
  
--- 295,306 ----
              }
              key.append("Month").append(toStyleName(baseStyle));
              break;
  
          case DAY_OF_WEEK:
!             // support standalone day names
!             if (isStandalone) {
                  key.append("standalone.");
              }
              key.append("Day").append(toStyleName(baseStyle));
              break;