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

*** 34,44 ****
--- 34,46 ----
  import java.text.spi.DateFormatSymbolsProvider;
  import java.text.spi.DecimalFormatSymbolsProvider;
  import java.text.spi.NumberFormatProvider;
  import java.util.Collections;
  import java.util.HashSet;
+ import java.util.List;
  import java.util.Locale;
+ import java.util.ResourceBundle;
  import java.util.ServiceLoader;
  import java.util.Set;
  import java.util.StringTokenizer;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
*** 377,386 ****
--- 379,395 ----
              }
          }
          return localeData;
      }
  
+     @Override
+     public List<Locale> getCandidateLocales(String baseName, Locale locale) {
+         return ResourceBundle.Control
+             .getNoFallbackControl(ResourceBundle.Control.FORMAT_DEFAULT)
+             .getCandidateLocales(baseName, locale);
+     }
+ 
      /**
       * Returns a list of the installed locales. Currently, this simply returns
       * the list of locales for which a sun.text.resources.FormatData bundle
       * exists. This bundle family happens to be the one with the broadest
       * locale coverage in the JRE.
*** 415,430 ****
  
          return tagset;
      }
  
      private static String createSupportedLocaleString(String category) {
!         // Directly call English tags, as we know it's in the base module.
!         String supportedLocaleString = EnLocaleDataMetaInfo.getSupportedLocaleString(category);
  
          // Use ServiceLoader to dynamically acquire installed locales' tags.
          try {
!             String nonENTags = AccessController.doPrivileged(new PrivilegedExceptionAction<String>() {
                  @Override
                  public String run() {
                      String tags = null;
                      for (LocaleDataMetaInfo ldmi :
                           ServiceLoader.loadInstalled(LocaleDataMetaInfo.class)) {
--- 424,439 ----
  
          return tagset;
      }
  
      private static String createSupportedLocaleString(String category) {
!         // Directly call Base tags, as we know it's in the base module.
!         String supportedLocaleString = BaseLocaleDataMetaInfo.getSupportedLocaleString(category);
  
          // Use ServiceLoader to dynamically acquire installed locales' tags.
          try {
!             String nonBaseTags = AccessController.doPrivileged(new PrivilegedExceptionAction<String>() {
                  @Override
                  public String run() {
                      String tags = null;
                      for (LocaleDataMetaInfo ldmi :
                           ServiceLoader.loadInstalled(LocaleDataMetaInfo.class)) {
*** 441,452 ****
                      }
                      return tags;
                  }
              });
  
!             if (nonENTags != null) {
!                 supportedLocaleString += " " + nonENTags;
              }
          }  catch (Exception e) {
              // catch any exception, and ignore them as if non-EN locales do not exist.
          }
  
--- 450,461 ----
                      }
                      return tags;
                  }
              });
  
!             if (nonBaseTags != null) {
!                 supportedLocaleString += " " + nonBaseTags;
              }
          }  catch (Exception e) {
              // catch any exception, and ignore them as if non-EN locales do not exist.
          }
  
*** 495,500 ****
--- 504,527 ----
                      locales[i] = Locale.forLanguageTag(currentToken);
              }
          }
          return locales;
      }
+ 
+     @Override
+     public boolean isSupportedProviderLocale(Locale locale,  Set<String> langtags) {
+         if (Locale.ROOT.equals(locale)) {
+             return true;
+         }
+ 
+         locale = locale.stripExtensions();
+         if (langtags.contains(locale.toLanguageTag())) {
+             return true;
+         }
+ 
+         String oldname = locale.toString().replace('_', '-');
+         return langtags.contains(oldname) ||
+                    "ja-JP-JP".equals(oldname) ||
+                    "th-TH-TH".equals(oldname) ||
+                    "no-NO-NY".equals(oldname);
+     }
  }