ADDITIONAL SYSTEM INFORMATION :
openjdk version "21-ea" 2023-09-19
OpenJDK Runtime Environment (build 21-ea+10-784)
OpenJDK 64-Bit Server VM (build 21-ea+10-784, mixed mode, sharing)



A DESCRIPTION OF THE PROBLEM :
Regression from JDK-8299571:
The fix to the above issue introduced a new bug when registering the same `java.time.zone.ZoneRulesProvider` twice it will in fact remove the provider from the registered ones again.

REGRESSION : Last worked in version 20

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a new `java.time.zone.ZoneRulesProvider` whichg provides a new unregistered ZoneId.
2. Call `java.time.zone.ZoneRulesProvider.registerProvider(zrp);` once. Provider will be registered.
3. Call `java.time.zone.ZoneRulesProvider.registerProvider(zrp);` again. Registering will fail with a `ZoneRulesException` as expected.
4. The newly introduced cleanup will remove the provider again.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The provider should still be registered for the ZoneId because it was registered successfully once.
ACTUAL -
The provider is unregistered and the ZoneId is not available.

---------- BEGIN SOURCE ----------
import java.util.Set;
import java.util.NavigableMap;
import java.time.ZoneId;
import java.time.zone.ZoneRules;
import java.time.zone.ZoneRulesProvider;
import java.time.zone.ZoneRulesException;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.assertThrows;

class ZoneRulesProviderTest {
    private static final String ZONE = "MyZone";
    @Test void registerProviderTwice() {
     // setup
        ZoneRulesProvider zrp = new ZoneRulesProvider() {
            @Override protected Set<String> provideZoneIds() {
                return Set.of(ZONE);
            }
            @Override protected ZoneRules provideRules(String zoneId, boolean forCaching) {
                return null;
            }
            @Override protected NavigableMap<String, ZoneRules> provideVersions(String zoneId) {
                return null;
            }
        };
        assertFalse(ZoneId.getAvailableZoneIds().contains(ZONE));
        ZoneRulesProvider.registerProvider(zrp);
        assertTrue(ZoneId.getAvailableZoneIds().contains(ZONE));
        assertNotNull(ZoneId.of(ZONE));
        
        // exercise
        assertThrows(ZoneRulesException.class, () -> ZoneRulesProvider.registerProvider(zrp));
        
        // verify - these will fail
        assertTrue(ZoneId.getAvailableZoneIds().contains(ZONE));
        assertNotNull(ZoneId.of(ZONE));
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Register the provider again (?)

FREQUENCY : always