Polishing

spring-aop/src/main/java/org/springframework/aop/support/DefaultIntroductionAdvisor.java

 /*
- * 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.
@@ -71,7 +71,8 @@ public class DefaultIntroductionAdvisor implements IntroductionAdvisor, ClassFil
 		if (introductionInfo != null) {
 			Class<?>[] introducedInterfaces = introductionInfo.getInterfaces();
 			if (introducedInterfaces.length == 0) {
-				throw new IllegalArgumentException("IntroductionAdviceSupport implements no interfaces");
+				throw new IllegalArgumentException(
+						"IntroductionInfo defines no interfaces to introduce: " + introductionInfo);
 			}
 			for (Class<?> ifc : introducedInterfaces) {
 				addInterface(ifc);

spring-beans/src/test/java/org/springframework/beans/factory/support/QualifierAnnotationAutowireBeanFactoryTests.java

 /*
- * 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.
@@ -244,7 +244,7 @@ public class QualifierAnnotationAutowireBeanFactoryTests {
 	@Target({ElementType.FIELD, ElementType.PARAMETER})
 	@Retention(RetentionPolicy.RUNTIME)
 	@Qualifier
-	private static @interface TestQualifier {
+	private @interface TestQualifier {
 	}
 
 }

spring-context/src/test/java/org/springframework/beans/factory/xml/QualifierAnnotationTests.java

 /*
- * 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.
@@ -47,8 +47,9 @@ import static org.springframework.util.ClassUtils.convertClassNameToResourcePath
 public class QualifierAnnotationTests {
 
 	private static final String CLASSNAME = QualifierAnnotationTests.class.getName();
+
 	private static final String CONFIG_LOCATION =
-		format("classpath:%s-context.xml", convertClassNameToResourcePath(CLASSNAME));
+			format("classpath:%s-context.xml", convertClassNameToResourcePath(CLASSNAME));
 
 
 	@Test

spring-oxm/spring-oxm.gradle

@@ -43,7 +43,7 @@ dependencies {
 }
 
 // JiBX compiler is currently not compatible with JDK 9+.
-// If customJavaHome has been set, we assume the custom JDK version is 9+.
+// If testToolchain has been set, we assume the custom JDK version is 9+.
 if ((JavaVersion.current() == JavaVersion.VERSION_1_8) && !project.hasProperty("testToolchain")) {
 	compileTestJava {
 		def bindingXml = "${projectDir}/src/test/resources/org/springframework/oxm/jibx/binding.xml"

spring-web/src/main/java/org/springframework/http/client/reactive/JettyClientHttpResponse.java

@@ -50,7 +50,7 @@ class JettyClientHttpResponse implements ClientHttpResponse {
 
 	private static final Pattern SAMESITE_PATTERN = Pattern.compile("(?i).*SameSite=(Strict|Lax|None).*");
 
-	private static final ClassLoader loader = JettyClientHttpResponse.class.getClassLoader();
+	private static final ClassLoader classLoader = JettyClientHttpResponse.class.getClassLoader();
 
 	private static final boolean jetty10Present;
 
@@ -64,7 +64,7 @@ class JettyClientHttpResponse implements ClientHttpResponse {
 
 	static {
 		try {
-			Class<?> httpFieldsClass = loader.loadClass("org.eclipse.jetty.http.HttpFields");
+			Class<?> httpFieldsClass = classLoader.loadClass("org.eclipse.jetty.http.HttpFields");
 			jetty10Present = httpFieldsClass.isInterface();
 		}
 		catch (ClassNotFoundException ex) {
@@ -144,7 +144,7 @@ class JettyClientHttpResponse implements ClientHttpResponse {
 		static {
 			try {
 				getHeadersMethod = Response.class.getMethod("getHeaders");
-				Class<?> type = loader.loadClass("org.eclipse.jetty.http.HttpField");
+				Class<?> type = classLoader.loadClass("org.eclipse.jetty.http.HttpField");
 				getNameMethod = type.getMethod("getName");
 				getValueMethod = type.getMethod("getValue");
 			}

spring-web/src/main/java/org/springframework/http/client/reactive/JettyHeadersAdapter.java

@@ -187,7 +187,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	private class EntryIterator implements Iterator<Entry<String, List<String>>> {
 
-		private Enumeration<String> names = headers.getFieldNames();
+		private final Enumeration<String> names = headers.getFieldNames();
 
 		@Override
 		public boolean hasNext() {
@@ -241,6 +241,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 		}
 	}
 
+
 	private final class HeaderNamesIterator implements Iterator<String> {
 
 		private final Iterator<String> iterator;

spring-web/src/main/java/org/springframework/http/server/reactive/JettyHeadersAdapter.java

@@ -187,7 +187,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 
 	private class EntryIterator implements Iterator<Entry<String, List<String>>> {
 
-		private Enumeration<String> names = headers.getFieldNames();
+		private final Enumeration<String> names = headers.getFieldNames();
 
 		@Override
 		public boolean hasNext() {
@@ -241,6 +241,7 @@ class JettyHeadersAdapter implements MultiValueMap<String, String> {
 		}
 	}
 
+
 	private final class HeaderNamesIterator implements Iterator<String> {
 
 		private final Iterator<String> iterator;