Annotate Object#equals parameter with @Nullable

Closes gh-23093

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

@@ -161,7 +161,7 @@ public final class FlashMap extends HashMap<String, Object> implements Comparabl
 	}
 
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(@Nullable Object other) {
 		if (this == other) {
 			return true;
 		}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfo.java

@@ -298,7 +298,7 @@ public final class RequestMappingInfo implements RequestCondition<RequestMapping
 	}
 
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(@Nullable Object other) {
 		if (this == other) {
 			return true;
 		}

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

@@ -30,6 +30,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.core.io.Resource;
+import org.springframework.lang.Nullable;
 import org.springframework.util.FileCopyUtils;
 import org.springframework.util.StringUtils;
 
@@ -231,7 +232,7 @@ public class CssLinkResourceTransformer extends ResourceTransformerSupport {
 		}
 
 		@Override
-		public boolean equals(Object other) {
+		public boolean equals(@Nullable Object other) {
 			if (this == other) {
 				return true;
 			}

spring-webmvc/src/main/java/org/springframework/web/servlet/view/script/ScriptTemplateView.java

@@ -423,7 +423,7 @@ public class ScriptTemplateView extends AbstractUrlBasedView {
 		}
 
 		@Override
-		public boolean equals(Object other) {
+		public boolean equals(@Nullable Object other) {
 			if (this == other) {
 				return true;
 			}