Use enhanced for loop where feasible

See gh-31916

spring-aop/src/main/java/org/springframework/aop/config/ConfigBeanDefinitionParser.java

@@ -201,9 +201,8 @@ class ConfigBeanDefinitionParser implements BeanDefinitionParser {
 			List<BeanReference> beanReferences = new ArrayList<>();
 
 			List<Element> declareParents = DomUtils.getChildElementsByTagName(aspectElement, DECLARE_PARENTS);
-			for (int i = METHOD_INDEX; i < declareParents.size(); i++) {
-				Element declareParentsElement = declareParents.get(i);
-				beanDefinitions.add(parseDeclareParents(declareParentsElement, parserContext));
+			for (Element declareParent : declareParents) {
+				beanDefinitions.add(parseDeclareParents(declareParent, parserContext));
 			}
 
 			// We have to parse "advice" and all the advice kinds in one loop, to get the

spring-beans/src/testFixtures/java/org/springframework/beans/testfixture/beans/GenericBean.java

@@ -23,7 +23,6 @@ import java.util.EnumMap;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -268,8 +267,8 @@ public class GenericBean<T> {
 
 	public void setCustomEnumSetMismatch(Set<String> customEnumSet) {
 		this.customEnumSet = new HashSet<>(customEnumSet.size());
-		for (Iterator<String> iterator = customEnumSet.iterator(); iterator.hasNext(); ) {
-			this.customEnumSet.add(CustomEnum.valueOf(iterator.next()));
+		for (String customEnumName : customEnumSet) {
+			this.customEnumSet.add(CustomEnum.valueOf(customEnumName));
 		}
 	}
 

spring-context/src/test/java/org/springframework/aop/framework/AbstractAopProxyTests.java

@@ -24,7 +24,6 @@ import java.rmi.MarshalException;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
@@ -1224,8 +1223,7 @@ public abstract class AbstractAopProxyTests {
 			@Override
 			public Object invoke(MethodInvocation invocation) throws Throwable {
 				ReflectiveMethodInvocation rmi = (ReflectiveMethodInvocation) invocation;
-				for (Iterator<String> it = rmi.getUserAttributes().keySet().iterator(); it.hasNext(); ){
-					Object key = it.next();
+				for (Object key : rmi.getUserAttributes().keySet()) {
 					assertThat(rmi.getUserAttributes().get(key)).isEqualTo(expectedValues.get(key));
 				}
 				rmi.getUserAttributes().putAll(valuesToAdd);

spring-context/src/test/java/org/springframework/aop/target/CommonsPool2TargetSourceTests.java

@@ -186,8 +186,8 @@ class CommonsPool2TargetSourceTests {
 		pooledInstances[9] = targetSource.getTarget();
 
 		// release all objects
-		for (int i = 0; i < pooledInstances.length; i++) {
-			targetSource.releaseTarget(pooledInstances[i]);
+		for (Object pooledInstance : pooledInstances) {
+			targetSource.releaseTarget(pooledInstance);
 		}
 	}
 

spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java

@@ -607,8 +607,8 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
 				// Restructure the resized reference array
 				if (resizing) {
 					Reference<K, V>[] restructured = createReferenceArray(restructureSize);
-					for (int i = 0; i < this.references.length; i++) {
-						ref = this.references[i];
+					for (Reference<K, V> reference : this.references) {
+						ref = reference;
 						while (ref != null) {
 							if (!toPurge.contains(ref)) {
 								Entry<K, V> entry = ref.get();

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/client/JettyXhrTransport.java

@@ -20,7 +20,6 @@ import java.io.ByteArrayOutputStream;
 import java.net.URI;
 import java.nio.ByteBuffer;
 import java.util.Enumeration;
-import java.util.Iterator;
 import java.util.concurrent.CompletableFuture;
 
 import org.eclipse.jetty.client.ContentResponse;
@@ -172,9 +171,7 @@ public class JettyXhrTransport extends AbstractXhrTransport implements Lifecycle
 
 	private static HttpHeaders toHttpHeaders(HttpFields httpFields) {
 		HttpHeaders responseHeaders = new HttpHeaders();
-		Iterator<String> names = httpFields.getFieldNamesCollection().iterator();
-		while (names.hasNext()) {
-			String name = names.next();
+		for (String name : httpFields.getFieldNamesCollection()) {
 			Enumeration<String> values = httpFields.getValues(name);
 			while (values.hasMoreElements()) {
 				String value = values.nextElement();