Make inner classes static when feasible

spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java

@@ -654,7 +654,7 @@ private Object resolvedCachedArgument(@Nullable String beanName, @Nullable Objec
 	/**
 	 * Base class representing injection information.
 	 */
-	private abstract class AutowiredElement extends InjectionMetadata.InjectedElement {
+	private abstract static class AutowiredElement extends InjectionMetadata.InjectedElement {
 
 		protected final boolean required;
 

spring-beans/src/main/java/org/springframework/beans/factory/aot/BeanDefinitionPropertyValueCodeGenerator.java

@@ -119,7 +119,7 @@ private interface Delegate {
 	/**
 	 * {@link Delegate} for {@code primitive} types.
 	 */
-	private class PrimitiveDelegate implements Delegate {
+	private static class PrimitiveDelegate implements Delegate {
 
 		private static final Map<Character, String> CHAR_ESCAPES;
 
@@ -177,7 +177,7 @@ private String escape(char ch) {
 	/**
 	 * {@link Delegate} for {@link String} types.
 	 */
-	private class StringDelegate implements Delegate {
+	private static class StringDelegate implements Delegate {
 
 		@Override
 		@Nullable
@@ -194,7 +194,7 @@ public CodeBlock generateCode(Object value, ResolvableType type) {
 	/**
 	 * {@link Delegate} for {@link Enum} types.
 	 */
-	private class EnumDelegate implements Delegate {
+	private static class EnumDelegate implements Delegate {
 
 		@Override
 		@Nullable
@@ -212,7 +212,7 @@ public CodeBlock generateCode(Object value, ResolvableType type) {
 	/**
 	 * {@link Delegate} for {@link Class} types.
 	 */
-	private class ClassDelegate implements Delegate {
+	private static class ClassDelegate implements Delegate {
 
 		@Override
 		@Nullable
@@ -229,7 +229,7 @@ public CodeBlock generateCode(Object value, ResolvableType type) {
 	/**
 	 * {@link Delegate} for {@link ResolvableType} types.
 	 */
-	private class ResolvableTypeDelegate implements Delegate {
+	private static class ResolvableTypeDelegate implements Delegate {
 
 		@Override
 		@Nullable
@@ -512,7 +512,7 @@ private <K, V> CodeBlock generateLinkedHashMapCode(Map<K, V> map,
 	/**
 	 * {@link Delegate} for {@link BeanReference} types.
 	 */
-	private class BeanReferenceDelegate implements Delegate {
+	private static class BeanReferenceDelegate implements Delegate {
 
 		@Override
 		@Nullable

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassPostProcessor.java

@@ -509,7 +509,7 @@ public Object postProcessBeforeInitialization(Object bean, String beanName) {
 	}
 
 
-	private class AotContribution implements BeanFactoryInitializationAotContribution {
+	private static class AotContribution implements BeanFactoryInitializationAotContribution {
 
 		private static final String BEAN_FACTORY_VARIABLE = BeanFactoryInitializationCode.BEAN_FACTORY_VARIABLE;
 

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

@@ -88,7 +88,7 @@ public void handleRequest(HttpServerExchange exchange) {
 	}
 
 
-	private class HandlerResultSubscriber implements Subscriber<Void> {
+	private static class HandlerResultSubscriber implements Subscriber<Void> {
 
 		private final HttpServerExchange exchange;
 

spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java

@@ -236,7 +236,7 @@ protected VersionStrategy getStrategyForPath(String requestPath) {
 	}
 
 
-	private class FileNameVersionedResource extends AbstractResource implements HttpResource {
+	private static class FileNameVersionedResource extends AbstractResource implements HttpResource {
 
 		private final Resource original;
 

spring-webflux/src/main/java/org/springframework/web/reactive/socket/server/upgrade/UndertowRequestUpgradeStrategy.java

@@ -82,7 +82,7 @@ public Mono<Void> upgrade(ServerWebExchange exchange, WebSocketHandler handler,
 	}
 
 
-	private class DefaultCallback implements WebSocketConnectionCallback {
+	private static class DefaultCallback implements WebSocketConnectionCallback {
 
 		private final HandshakeInfo handshakeInfo;
 

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java

@@ -232,7 +232,7 @@ protected VersionStrategy getStrategyForPath(String requestPath) {
 	}
 
 
-	private class FileNameVersionedResource extends AbstractResource implements HttpResource {
+	private static class FileNameVersionedResource extends AbstractResource implements HttpResource {
 
 		private final Resource original;
 

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/handler/XhrStreamingTransportHandler.java

@@ -75,7 +75,7 @@ protected SockJsFrameFormat getFrameFormat(ServerHttpRequest request) {
 	}
 
 
-	private class XhrStreamingSockJsSession extends StreamingSockJsSession {
+	private static class XhrStreamingSockJsSession extends StreamingSockJsSession {
 
 		public XhrStreamingSockJsSession(String sessionId, SockJsServiceConfig config,
 				WebSocketHandler wsHandler, Map<String, Object> attributes) {