Annotate Object#equals parameter with @Nullable

Closes gh-23093

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ExchangeFilterFunctions.java

@@ -29,6 +29,7 @@ import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.reactive.function.BodyExtractors;
 
@@ -171,7 +172,7 @@ public abstract class ExchangeFilterFunctions {
 		}
 
 		@Override
-		public boolean equals(Object other) {
+		public boolean equals(@Nullable Object other) {
 			if (this == other) {
 				return true;
 			}

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

@@ -36,6 +36,7 @@ import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.StreamUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.server.ServerWebExchange;
@@ -284,7 +285,7 @@ public class CssLinkResourceTransformer extends ResourceTransformerSupport {
 		}
 
 		@Override
-		public boolean equals(Object other) {
+		public boolean equals(@Nullable Object other) {
 			if (this == other) {
 				return true;
 			}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/RequestMappingInfo.java

@@ -288,7 +288,7 @@ 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-webflux/src/main/java/org/springframework/web/reactive/socket/CloseStatus.java

@@ -190,7 +190,7 @@ public final class CloseStatus {
 	}
 
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(@Nullable Object other) {
 		if (this == other) {
 			return true;
 		}

spring-webflux/src/main/java/org/springframework/web/reactive/socket/WebSocketMessage.java

@@ -20,6 +20,7 @@ import java.nio.charset.StandardCharsets;
 
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -117,7 +118,7 @@ public class WebSocketMessage {
 
 
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(@Nullable Object other) {
 		if (this == other) {
 			return true;
 		}