HHH-12560 - Make sure only one Service registration (initiator/provided) exists per role

- additional test - this one needed a minor change.. all tests implicitly use values defined in `hibernate.properties`, which hibernate-core has.  This lead to `#getFallback` being called, which was the intended solution.  The fix for that was simply the next point.
- added the ability to clear the settings contained on StandardServiceRegistryBuilder.  This is used in the test to make sure that no explicit RegionFactory is set.

hibernate-core/src/main/java/org/hibernate/boot/registry/StandardServiceRegistryBuilder.java

@@ -208,6 +208,10 @@ public class StandardServiceRegistryBuilder {
 		return this;
 	}
 
+	public void clearSettings() {
+		settings.clear();
+	}
+
 	/**
 	 * Adds a service initiator.
 	 *

hibernate-core/src/test/java/org/hibernate/service/ServiceContributorTest.java

@@ -11,11 +11,15 @@ import java.util.Map;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
 import org.hibernate.cache.internal.RegionFactoryInitiator;
 import org.hibernate.cache.spi.RegionFactory;
+import org.hibernate.cfg.AvailableSettings;
 import org.hibernate.service.spi.ServiceRegistryImplementor;
 
+import org.hibernate.testing.cache.CachingRegionFactory;
 import org.hibernate.testing.junit4.BaseUnitTestCase;
 import org.junit.Test;
 
+import static org.hibernate.testing.junit4.ExtraAssertions.assertTyping;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 /**
@@ -23,32 +27,62 @@ import static org.junit.Assert.assertTrue;
  */
 public class ServiceContributorTest extends BaseUnitTestCase {
 	@Test
-	public void overrideInitiator() {
+	public void overrideCachingInitiator() {
 		StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder();
-
+		ssrb.clearSettings();
-		class MyRegionFactoryInitiator extends RegionFactoryInitiator {
-			private boolean called = false;
-
-			@Override
-			public RegionFactory initiateService(
-					Map configurationValues,
-					ServiceRegistryImplementor registry) {
-				called = true;
-				return super.initiateService( configurationValues, registry );
-			}
-		}
 
 		final MyRegionFactoryInitiator initiator = new MyRegionFactoryInitiator();
-
 		ssrb.addInitiator( initiator );
 
 		final ServiceRegistryImplementor registry = (ServiceRegistryImplementor) ssrb.build();
 		try {
-			registry.getService( RegionFactory.class );
+			final RegionFactory regionFactory = registry.getService( RegionFactory.class );
 			assertTrue( initiator.called );
+			assertTyping( MyRegionFactory.class, regionFactory );
 		}
 		finally {
 			StandardServiceRegistryBuilder.destroy( registry );
 		}
 	}
+	@Test
+	public void overrideCachingInitiatorExplicitSet() {
+		StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder();
+
+		final MyRegionFactoryInitiator initiator = new MyRegionFactoryInitiator();
+		ssrb.addInitiator( initiator );
+		ssrb.applySetting( AvailableSettings.CACHE_REGION_FACTORY, new MyRegionFactory() );
+
+		final ServiceRegistryImplementor registry = (ServiceRegistryImplementor) ssrb.build();
+		try {
+			registry.getService( RegionFactory.class );
+			assertFalse( initiator.called );
+		}
+		finally {
+			StandardServiceRegistryBuilder.destroy( registry );
+		}
+	}
+
+	class MyRegionFactoryInitiator extends RegionFactoryInitiator {
+		private boolean called = false;
+
+		@Override
+		protected RegionFactory getFallback(
+				Map configurationValues,
+				ServiceRegistryImplementor registry) {
+			called = true;
+			return new MyRegionFactory();
+		}
+
+//			@Override
+//			public RegionFactory initiateService(
+//					Map configurationValues,
+//					ServiceRegistryImplementor registry) {
+//				called = true;
+//				return super.initiateService( configurationValues, registry );
+//			}
+	}
+
+	class MyRegionFactory extends CachingRegionFactory {
+	}
+
 }