Remove JDK 9 workarounds etc

See gh-17778

spring-aop/src/main/java/org/springframework/aop/framework/AopProxyUtils.java

@@ -33,7 +33,6 @@ import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
-import org.springframework.util.ReflectionUtils;
 
 /**
  * Utility methods for AOP proxy factories.
@@ -48,11 +47,6 @@ import org.springframework.util.ReflectionUtils;
  */
 public abstract class AopProxyUtils {
 
-	// JDK 17 Class.isSealed() method available?
-	@Nullable
-	private static final Method isSealedMethod = ClassUtils.getMethodIfAvailable(Class.class, "isSealed");
-
-
 	/**
 	 * Obtain the singleton target object behind the given proxy, if any.
 	 * @param candidate the (potential) proxy to check
@@ -142,7 +136,7 @@ public abstract class AopProxyUtils {
 		List<Class<?>> proxiedInterfaces = new ArrayList<>(specifiedInterfaces.length + 3);
 		for (Class<?> ifc : specifiedInterfaces) {
 			// Only non-sealed interfaces are actually eligible for JDK proxying (on JDK 17)
-			if (isSealedMethod == null || Boolean.FALSE.equals(ReflectionUtils.invokeMethod(isSealedMethod, ifc))) {
+			if (!ifc.isSealed()) {
 				proxiedInterfaces.add(ifc);
 			}
 		}

spring-core/src/main/java/org/springframework/cglib/core/ReflectUtils.java

@@ -260,7 +260,7 @@ public class ReflectUtils {
 		return newInstance(getConstructor(type, parameterTypes), args);
 	}
 
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	public static Object newInstance(final Constructor cstruct, final Object[] args) {
 		boolean flag = cstruct.isAccessible();
 		try {
@@ -439,7 +439,7 @@ public class ReflectUtils {
 		return defineClass(className, b, loader, protectionDomain, null);
 	}
 
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	public static Class defineClass(String className, byte[] b, ClassLoader loader,
 			ProtectionDomain protectionDomain, Class<?> contextClass) throws Exception {
 

spring-core/src/main/java/org/springframework/cglib/core/package-info.java

@@ -5,6 +5,6 @@
  *
  * <p>As this repackaging happens at the class file level, sources
  * and javadocs are not available here... except for a few files
- * that have been patched for Spring's purposes on JDK 9/10/11.
+ * that have been patched for Spring's purposes on JDK 9-17.
  */
 package org.springframework.cglib.core;

spring-core/src/main/java/org/springframework/cglib/proxy/package-info.java

@@ -5,6 +5,6 @@
  *
  * <p>As this repackaging happens at the class file level, sources
  * and javadocs are not available here... except for a few files
- * that have been patched for Spring's purposes on JDK 9/10/11.
+ * that have been patched for Spring's purposes on JDK 9-17.
  */
 package org.springframework.cglib.proxy;

spring-core/src/main/java/org/springframework/core/ReactiveAdapterRegistry.java

@@ -16,17 +16,18 @@
 
 package org.springframework.core;
 
-import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionStage;
+import java.util.concurrent.Flow;
 import java.util.function.Function;
 
 import kotlinx.coroutines.CompletableDeferredKt;
 import kotlinx.coroutines.Deferred;
 import org.reactivestreams.Publisher;
+import reactor.adapter.JdkFlowAdapter;
 import reactor.blockhound.BlockHound;
 import reactor.blockhound.integration.BlockHoundIntegration;
 import reactor.core.publisher.Flux;
@@ -36,7 +37,6 @@ import rx.RxReactiveStreams;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
-import org.springframework.util.ReflectionUtils;
 
 /**
  * A registry of adapters to adapt Reactive Streams {@link Publisher} to/from
@@ -350,28 +350,12 @@ public class ReactiveAdapterRegistry {
 	private static class ReactorJdkFlowAdapterRegistrar {
 
 		void registerAdapter(ReactiveAdapterRegistry registry) {
-			// TODO: remove reflection when build requires JDK 9+
-
-			try {
-				String publisherName = "java.util.concurrent.Flow.Publisher";
-				Class<?> publisherClass = ClassUtils.forName(publisherName, getClass().getClassLoader());
-
-				String adapterName = "reactor.adapter.JdkFlowAdapter";
-				Class<?> flowAdapterClass = ClassUtils.forName(adapterName,  getClass().getClassLoader());
-
-				Method toFluxMethod = flowAdapterClass.getMethod("flowPublisherToFlux", publisherClass);
-				Method toFlowMethod = flowAdapterClass.getMethod("publisherToFlowPublisher", Publisher.class);
-				Object emptyFlow = ReflectionUtils.invokeMethod(toFlowMethod, null, Flux.empty());
-
-				registry.registerReactiveType(
-						ReactiveTypeDescriptor.multiValue(publisherClass, () -> emptyFlow),
-						source -> (Publisher<?>) ReflectionUtils.invokeMethod(toFluxMethod, null, source),
-						publisher -> ReflectionUtils.invokeMethod(toFlowMethod, null, publisher)
-				);
-			}
-			catch (Throwable ex) {
-				// Ignore
-			}
+			Flow.Publisher<?> emptyFlow = JdkFlowAdapter.publisherToFlowPublisher(Flux.empty());
+			registry.registerReactiveType(
+					ReactiveTypeDescriptor.multiValue(Flow.Publisher.class, () -> emptyFlow),
+					source -> JdkFlowAdapter.flowPublisherToFlux((Flow.Publisher<?>) source),
+					JdkFlowAdapter::publisherToFlowPublisher
+			);
 		}
 	}
 

spring-core/src/main/java/org/springframework/core/convert/support/ByteBufferConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.core.convert.support;
 
-import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.HashSet;
@@ -122,10 +121,7 @@ final class ByteBufferConverter implements ConditionalGenericConverter {
 		ByteBuffer byteBuffer = ByteBuffer.allocate(bytes.length);
 		byteBuffer.put(bytes);
 
-		// Extra cast necessary for compiling on JDK 9 plus running on JDK 8, since
-		// otherwise the overridden ByteBuffer-returning rewind method would be chosen
-		// which isn't available on JDK 8.
-		return ((Buffer) byteBuffer).rewind();
+		return byteBuffer.rewind();
 	}
 
 }

spring-core/src/main/java/org/springframework/core/io/buffer/DefaultDataBuffer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,6 @@ package org.springframework.core.io.buffer;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import java.util.Arrays;
@@ -333,18 +332,14 @@ public class DefaultDataBuffer implements DataBuffer {
 	public DefaultDataBuffer slice(int index, int length) {
 		checkIndex(index, length);
 		int oldPosition = this.byteBuffer.position();
-		// Explicit access via Buffer base type for compatibility
-		// with covariant return type on JDK 9's ByteBuffer...
-		Buffer buffer = this.byteBuffer;
 		try {
-			buffer.position(index);
+			this.byteBuffer.position(index);
 			ByteBuffer slice = this.byteBuffer.slice();
-			// Explicit cast for compatibility with covariant return type on JDK 9's ByteBuffer
 			slice.limit(length);
 			return new SlicedDefaultDataBuffer(slice, this.dataBufferFactory, length);
 		}
 		finally {
-			buffer.position(oldPosition);
+			this.byteBuffer.position(oldPosition);
 		}
 	}
 
@@ -358,11 +353,8 @@ public class DefaultDataBuffer implements DataBuffer {
 		checkIndex(index, length);
 
 		ByteBuffer duplicate = this.byteBuffer.duplicate();
-		// Explicit access via Buffer base type for compatibility
-		// with covariant return type on JDK 9's ByteBuffer...
-		Buffer buffer = duplicate;
-		buffer.position(index);
-		buffer.limit(index + length);
+		duplicate.position(index);
+		duplicate.limit(index + length);
 		return duplicate.slice();
 	}
 

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

@@ -778,7 +778,7 @@ public abstract class ClassUtils {
 	 * conflicting method signatures (or a similar constraint is violated)
 	 * @see java.lang.reflect.Proxy#getProxyClass
 	 */
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	public static Class<?> createCompositeInterface(Class<?>[] interfaces, @Nullable ClassLoader classLoader) {
 		Assert.notEmpty(interfaces, "Interface array must not be empty");
 		return Proxy.getProxyClass(classLoader, interfaces);

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

@@ -194,7 +194,7 @@ public abstract class ReflectionUtils {
 	 * @param ctor the constructor to make accessible
 	 * @see java.lang.reflect.Constructor#setAccessible
 	 */
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	public static void makeAccessible(Constructor<?> ctor) {
 		if ((!Modifier.isPublic(ctor.getModifiers()) ||
 				!Modifier.isPublic(ctor.getDeclaringClass().getModifiers())) && !ctor.isAccessible()) {
@@ -563,7 +563,7 @@ public abstract class ReflectionUtils {
 	 * @param method the method to make accessible
 	 * @see java.lang.reflect.Method#setAccessible
 	 */
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	public static void makeAccessible(Method method) {
 		if ((!Modifier.isPublic(method.getModifiers()) ||
 				!Modifier.isPublic(method.getDeclaringClass().getModifiers())) && !method.isAccessible()) {
@@ -775,7 +775,7 @@ public abstract class ReflectionUtils {
 	 * @param field the field to make accessible
 	 * @see java.lang.reflect.Field#setAccessible
 	 */
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	public static void makeAccessible(Field field) {
 		if ((!Modifier.isPublic(field.getModifiers()) ||
 				!Modifier.isPublic(field.getDeclaringClass().getModifiers()) ||

spring-core/src/test/java/org/springframework/util/ObjectUtilsTests.java

@@ -251,7 +251,7 @@ class ObjectUtilsTests {
 	@Deprecated
 	void hashCodeWithDouble() {
 		double dbl = 9830.43;
-		int expected = (new Double(dbl)).hashCode();
+		int expected = Double.valueOf(dbl).hashCode();
 		assertThat(ObjectUtils.hashCode(dbl)).isEqualTo(expected);
 	}
 

spring-jcl/src/main/java/org/apache/commons/logging/LogAdapter.java

@@ -681,7 +681,7 @@ final class LogAdapter {
 			setSourceMethodName(sourceMethodName);
 		}
 
-		@SuppressWarnings("deprecation")  // setMillis is deprecated in JDK 9
+		@SuppressWarnings("deprecation")
 		protected Object writeReplace() {
 			LogRecord serialized = new LogRecord(getLevel(), getMessage());
 			serialized.setLoggerName(getLoggerName());

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,6 @@
 package org.springframework.messaging.simp.stomp;
 
 import java.io.ByteArrayOutputStream;
-import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
@@ -134,11 +133,7 @@ public class StompDecoder {
 	private Message<byte[]> decodeMessage(ByteBuffer byteBuffer, @Nullable MultiValueMap<String, String> headers) {
 		Message<byte[]> decodedMessage = null;
 		skipEol(byteBuffer);
-
-		// Explicit mark/reset access via Buffer base type for compatibility
-		// with covariant return type on JDK 9's ByteBuffer...
-		Buffer buffer = byteBuffer;
-		buffer.mark();
+		byteBuffer.mark();
 
 		String command = readCommand(byteBuffer);
 		if (command.length() > 0) {
@@ -176,7 +171,7 @@ public class StompDecoder {
 						headers.putAll(map);
 					}
 				}
-				buffer.reset();
+				byteBuffer.reset();
 			}
 		}
 		else {
@@ -357,8 +352,7 @@ public class StompDecoder {
 					throw new StompConversionException("'\\r' must be followed by '\\n'");
 				}
 			}
-			// Explicit cast for compatibility with covariant return type on JDK 9's ByteBuffer
-			((Buffer) byteBuffer).position(byteBuffer.position() - 1);
+			byteBuffer.position(byteBuffer.position() - 1);
 		}
 		return false;
 	}

spring-oxm/src/main/java/org/springframework/oxm/support/AbstractMarshaller.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -189,7 +189,7 @@ public abstract class AbstractMarshaller implements Marshaller, Unmarshaller {
 	 * @return the XMLReader
 	 * @throws SAXException if thrown by JAXP methods
 	 */
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	protected XMLReader createXmlReader() throws SAXException {
 		XMLReader xmlReader = org.xml.sax.helpers.XMLReaderFactory.createXMLReader();
 		xmlReader.setFeature("http://apache.org/xml/features/disallow-doctype-decl", !isSupportDtd());

spring-web/src/main/java/org/springframework/http/codec/xml/XmlEventDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -122,7 +122,6 @@ public class XmlEventDecoder extends AbstractDecoder<XMLEvent> {
 
 
 	@Override
-	@SuppressWarnings({"rawtypes", "unchecked", "cast"})  // XMLEventReader is Iterator<Object> on JDK 9
 	public Flux<XMLEvent> decode(Publisher<DataBuffer> input, ResolvableType elementType,
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
 
@@ -137,7 +136,7 @@ public class XmlEventDecoder extends AbstractDecoder<XMLEvent> {
 					.flatMapIterable(buffer -> {
 						try {
 							InputStream is = buffer.asInputStream();
-							Iterator eventReader = inputFactory.createXMLEventReader(is);
+							Iterator<Object> eventReader = inputFactory.createXMLEventReader(is);
 							List<XMLEvent> result = new ArrayList<>();
 							eventReader.forEachRemaining(event -> result.add((XMLEvent) event));
 							return result;

spring-web/src/main/java/org/springframework/http/converter/xml/SourceHttpMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -197,7 +197,7 @@ public class SourceHttpMessageConverter<T extends Source> extends AbstractHttpMe
 		}
 	}
 
-	@SuppressWarnings("deprecation")  // on JDK 9
+	@SuppressWarnings("deprecation")
 	private SAXSource readSAXSource(InputStream body, HttpInputMessage inputMessage) throws IOException {
 		try {
 			XMLReader xmlReader = org.xml.sax.helpers.XMLReaderFactory.createXMLReader();