HHH-12686 Replace EmptyIterator with emptyIterator

hibernate-core/src/main/java/org/hibernate/collection/internal/AbstractPersistentCollection.java

@@ -33,7 +33,6 @@ import org.hibernate.internal.CoreLogging;
 import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.internal.SessionFactoryRegistry;
 import org.hibernate.internal.util.MarkerObject;
-import org.hibernate.internal.util.collections.EmptyIterator;
 import org.hibernate.internal.util.collections.IdentitySet;
 import org.hibernate.persister.collection.CollectionPersister;
 import org.hibernate.persister.entity.EntityPersister;
@@ -784,7 +783,7 @@ public abstract class AbstractPersistentCollection implements Serializable, Pers
 			};
 		}
 		else {
-			return EmptyIterator.INSTANCE;
+			return Collections.emptyIterator();
 		}
 	}
 

hibernate-core/src/main/java/org/hibernate/engine/query/spi/HQLQueryPlan.java

@@ -34,7 +34,6 @@ import org.hibernate.hql.spi.QueryTranslatorFactory;
 import org.hibernate.internal.CoreLogging;
 import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.internal.util.collections.ArrayHelper;
-import org.hibernate.internal.util.collections.EmptyIterator;
 import org.hibernate.internal.util.collections.IdentitySet;
 import org.hibernate.internal.util.collections.JoinedIterator;
 import org.hibernate.query.internal.ParameterMetadataImpl;
@@ -308,7 +307,7 @@ public class HQLQueryPlan implements Serializable {
 			queryParameters.traceParameters( session.getFactory() );
 		}
 		if ( translators.length == 0 ) {
-			return EmptyIterator.INSTANCE;
+			return Collections.emptyIterator();
 		}
 
 		final boolean many = translators.length > 1;

hibernate-core/src/main/java/org/hibernate/internal/util/collections/EmptyIterator.java

@@ -1,32 +0,0 @@
-/*
- * Hibernate, Relational Persistence for Idiomatic Java
- *
- * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
- * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
- */
-package org.hibernate.internal.util.collections;
-
-import java.util.Iterator;
-
-/**
- * @author Gavin King
- */
-public final class EmptyIterator implements Iterator {
-
-	public static final Iterator INSTANCE = new EmptyIterator();
-
-	public boolean hasNext() {
-		return false;
-	}
-
-	public Object next() {
-		throw new UnsupportedOperationException();
-	}
-
-	public void remove() {
-		throw new UnsupportedOperationException();
-	}
-
-	private EmptyIterator() {}
-
-}

hibernate-core/src/main/java/org/hibernate/internal/util/collections/JoinedIterable.java

@@ -6,6 +6,7 @@
  */
 package org.hibernate.internal.util.collections;
 
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
@@ -76,7 +77,7 @@ public class JoinedIterable<T> implements Iterable<T> {
 
 			if ( currentIterator == null) {
 				if( iterables.size() == 0  ) {
-					currentIterator = EmptyIterator.INSTANCE;
+					currentIterator = Collections.emptyIterator();
 				}
 				else {
 					currentIterator = iterables.get( 0 ).iterator();

hibernate-core/src/main/java/org/hibernate/mapping/PersistentClass.java

@@ -8,6 +8,7 @@ package org.hibernate.mapping;
 
 import java.io.Serializable;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -23,7 +24,6 @@ import org.hibernate.engine.spi.ExecuteUpdateResultCheckStyle;
 import org.hibernate.engine.spi.Mapping;
 import org.hibernate.internal.FilterConfiguration;
 import org.hibernate.internal.util.StringHelper;
-import org.hibernate.internal.util.collections.EmptyIterator;
 import org.hibernate.internal.util.collections.JoinedIterator;
 import org.hibernate.internal.util.collections.SingletonIterator;
 import org.hibernate.service.ServiceRegistry;
@@ -888,7 +888,7 @@ public abstract class PersistentClass implements AttributeContainer, Serializabl
 	}
 
 	protected Iterator getDiscriminatorColumnIterator() {
-		return EmptyIterator.INSTANCE;
+		return Collections.emptyIterator();
 	}
 
 	protected void checkColumnDuplication() {

hibernate-core/src/main/java/org/hibernate/query/internal/AbstractProducedQuery.java

@@ -59,7 +59,6 @@ import org.hibernate.internal.EmptyScrollableResults;
 import org.hibernate.internal.EntityManagerMessageLogger;
 import org.hibernate.internal.HEMLogging;
 import org.hibernate.internal.util.collections.ArrayHelper;
-import org.hibernate.internal.util.collections.EmptyIterator;
 import org.hibernate.jpa.QueryHints;
 import org.hibernate.jpa.TypedParameterValue;
 import org.hibernate.jpa.graph.internal.EntityGraphImpl;
@@ -1443,7 +1442,7 @@ public abstract class AbstractProducedQuery<R> implements QueryImplementor<R> {
 	@SuppressWarnings("unchecked")
 	protected Iterator<R> doIterate() {
 		if (getMaxResults() == 0){
-			return EmptyIterator.INSTANCE;
+			return Collections.emptyIterator();
 		}
 		return getProducer().iterate(
 				getQueryParameterBindings().expandListValuedParameters( getQueryString(), getProducer() ),