Polishing

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -98,7 +98,9 @@ public final class ReactiveTypeDescriptor {
 	 */
 	public Object getEmptyValue() {
 		Assert.state(this.emptySupplier != null, "Empty values not supported");
-		return this.emptySupplier.get();
+		Object emptyValue = this.emptySupplier.get();
+		Assert.notNull(emptyValue, "Invalid null return value from emptySupplier");
+		return emptyValue;
 	}
 
 	/**
@@ -130,7 +132,7 @@ public final class ReactiveTypeDescriptor {
 
 
 	/**
-	 * Descriptor for a reactive type that can produce 0..N values.
+	 * Descriptor for a reactive type that can produce {@code 0..N} values.
 	 * @param type the reactive type
 	 * @param emptySupplier a supplier of an empty-value instance of the reactive type
 	 */

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -747,7 +747,7 @@ public class ResolvableType implements Serializable {
 	 * Convenience method that will {@link #getGenerics() get} and
 	 * {@link #resolve() resolve} generic parameters.
 	 * @return an array of resolved generic parameters (the resulting array
-	 * will never be {@code null}, but it may contain {@code null} elements})
+	 * will never be {@code null}, but it may contain {@code null} elements)
 	 * @see #getGenerics()
 	 * @see #resolve()
 	 */

spring-core/src/main/java/org/springframework/core/codec/Decoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -95,20 +95,19 @@ public interface Decoder<T> {
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) throws DecodingException {
 
 		CompletableFuture<T> future = decodeToMono(Mono.just(buffer), targetType, mimeType, hints).toFuture();
-		Assert.state(future.isDone(), "DataBuffer decoding should have completed.");
+		Assert.state(future.isDone(), "DataBuffer decoding should have completed");
 
-		Throwable failure;
 		try {
 			return future.get();
 		}
 		catch (ExecutionException ex) {
-			failure = ex.getCause();
+			Throwable cause = ex.getCause();
+			throw (cause instanceof CodecException codecException ? codecException :
+					new DecodingException("Failed to decode: " + (cause != null ? cause.getMessage() : ex), cause));
 		}
 		catch (InterruptedException ex) {
-			failure = ex;
+			throw new DecodingException("Interrupted during decode", ex);
 		}
-		throw (failure instanceof CodecException codecException ? codecException :
-				new DecodingException("Failed to decode: " + failure.getMessage(), failure));
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/codec/ResourceDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -76,10 +76,11 @@ public class ResourceDecoder extends AbstractDataBufferDecoder<Resource> {
 		}
 
 		Class<?> clazz = elementType.toClass();
-		String filename = hints != null ? (String) hints.get(FILENAME_HINT) : null;
+		String filename = (hints != null ? (String) hints.get(FILENAME_HINT) : null);
 		if (clazz == InputStreamResource.class) {
 			return new InputStreamResource(new ByteArrayInputStream(bytes)) {
 				@Override
+				@Nullable
 				public String getFilename() {
 					return filename;
 				}
@@ -92,6 +93,7 @@ public class ResourceDecoder extends AbstractDataBufferDecoder<Resource> {
 		else if (Resource.class.isAssignableFrom(clazz)) {
 			return new ByteArrayResource(bytes) {
 				@Override
+				@Nullable
 				public String getFilename() {
 					return filename;
 				}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -136,7 +136,7 @@ final class ObjectToObjectConverter implements ConditionalGenericConverter {
 	@Nullable
 	private static Executable getValidatedExecutable(Class<?> targetClass, Class<?> sourceClass) {
 		Executable executable = conversionExecutableCache.get(targetClass);
-		if (isApplicable(executable, sourceClass)) {
+		if (executable != null && isApplicable(executable, sourceClass)) {
 			return executable;
 		}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -62,7 +62,7 @@ import org.springframework.util.Assert;
  */
 public abstract class DataBufferUtils {
 
-	private final static Log logger = LogFactory.getLog(DataBufferUtils.class);
+	private static final Log logger = LogFactory.getLog(DataBufferUtils.class);
 
 	private static final Consumer<DataBuffer> RELEASE_CONSUMER = DataBufferUtils::release;
 
@@ -745,7 +745,7 @@ public abstract class DataBufferUtils {
 	 */
 	private static class SingleByteMatcher implements NestedMatcher {
 
-		static SingleByteMatcher NEWLINE_MATCHER = new SingleByteMatcher(new byte[] {10});
+		static final SingleByteMatcher NEWLINE_MATCHER = new SingleByteMatcher(new byte[] {10});
 
 		private final byte[] delimiter;
 
@@ -784,7 +784,7 @@ public abstract class DataBufferUtils {
 	/**
 	 * Base class for a {@link NestedMatcher}.
 	 */
-	private static abstract class AbstractNestedMatcher implements NestedMatcher {
+	private abstract static class AbstractNestedMatcher implements NestedMatcher {
 
 		private final byte[] delimiter;
 
@@ -990,7 +990,7 @@ public abstract class DataBufferUtils {
 			DataBuffer.ByteBufferIterator iterator = dataBuffer.writableByteBuffers();
 			Assert.state(iterator.hasNext(), "No ByteBuffer available");
 			ByteBuffer byteBuffer = iterator.next();
-			Attachment attachment = new Attachment(dataBuffer,  iterator);
+			Attachment attachment = new Attachment(dataBuffer, iterator);
 			this.channel.read(byteBuffer, this.position.get(), attachment, this);
 		}
 
@@ -999,7 +999,7 @@ public abstract class DataBufferUtils {
 			attachment.iterator().close();
 			DataBuffer dataBuffer = attachment.dataBuffer();
 
-			if (this.state.get().equals(State.DISPOSED)) {
+			if (this.state.get() == State.DISPOSED) {
 				release(dataBuffer);
 				closeChannel(this.channel);
 				return;
@@ -1030,13 +1030,13 @@ public abstract class DataBufferUtils {
 		}
 
 		@Override
-		public void failed(Throwable exc, Attachment attachment) {
+		public void failed(Throwable ex, Attachment attachment) {
 			attachment.iterator().close();
 			release(attachment.dataBuffer());
 
 			closeChannel(this.channel);
 			this.state.set(State.DISPOSED);
-			this.sink.error(exc);
+			this.sink.error(ex);
 		}
 
 		private enum State {
@@ -1095,7 +1095,6 @@ public abstract class DataBufferUtils {
 		public Context currentContext() {
 			return Context.of(this.sink.contextView());
 		}
-
 	}
 
 
@@ -1190,13 +1189,13 @@ public abstract class DataBufferUtils {
 		}
 
 		@Override
-		public void failed(Throwable exc, Attachment attachment) {
+		public void failed(Throwable ex, Attachment attachment) {
 			attachment.iterator().close();
 
 			this.sink.next(attachment.dataBuffer());
 			this.writing.set(false);
 
-			this.sink.error(exc);
+			this.sink.error(ex);
 		}
 
 		@Override
@@ -1205,9 +1204,6 @@ public abstract class DataBufferUtils {
 		}
 
 		private record Attachment(ByteBuffer byteBuffer, DataBuffer dataBuffer, DataBuffer.ByteBufferIterator iterator) {}
-
-
 	}
 
-
 }

spring-core/src/main/java/org/springframework/core/metrics/DefaultApplicationStartup.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -20,6 +20,8 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.function.Supplier;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Default "no op" {@code ApplicationStartup} implementation.
  *
@@ -52,6 +54,7 @@ class DefaultApplicationStartup implements ApplicationStartup {
 		}
 
 		@Override
+		@Nullable
 		public Long getParentId() {
 			return null;
 		}
@@ -73,7 +76,6 @@ class DefaultApplicationStartup implements ApplicationStartup {
 
 		@Override
 		public void end() {
-
 		}
 
 

spring-core/src/main/java/org/springframework/core/type/filter/AbstractTypeHierarchyTraversingFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -73,20 +73,20 @@ public abstract class AbstractTypeHierarchyTraversingFilter implements TypeFilte
 				// Optimization to avoid creating ClassReader for superclass.
 				Boolean superClassMatch = matchSuperClass(superClassName);
 				if (superClassMatch != null) {
-					if (superClassMatch.booleanValue()) {
+					if (superClassMatch) {
 						return true;
 					}
 				}
 				else {
 					// Need to read superclass to determine a match...
 					try {
-						if (match(metadata.getSuperClassName(), metadataReaderFactory)) {
+						if (match(superClassName, metadataReaderFactory)) {
 							return true;
 						}
 					}
 					catch (IOException ex) {
 						if (logger.isDebugEnabled()) {
-							logger.debug("Could not read superclass [" + metadata.getSuperClassName() +
+							logger.debug("Could not read superclass [" + superClassName +
 									"] of type-filtered class [" + metadata.getClassName() + "]");
 						}
 					}
@@ -99,7 +99,7 @@ public abstract class AbstractTypeHierarchyTraversingFilter implements TypeFilte
 				// Optimization to avoid creating ClassReader for superclass
 				Boolean interfaceMatch = matchInterface(ifc);
 				if (interfaceMatch != null) {
-					if (interfaceMatch.booleanValue()) {
+					if (interfaceMatch) {
 						return true;
 					}
 				}