Upgrade to Tomcat 9.0.55, Undertow 2.2.13, RxJava 3.1.3, SmallRye Mutiny 1.2, Joda-Time 2.10.13, JRuby 9.2.20.1, HtmlUnit 2.55, Checkstyle 9.2

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

@@ -123,6 +123,7 @@ public class TomcatRequestUpgradeStrategy implements RequestUpgradeStrategy {
 	}
 
 
+	@SuppressWarnings("deprecation")  // for old doUpgrade variant in Tomcat 9.0.55
 	@Override
 	public Mono<Void> upgrade(ServerWebExchange exchange, WebSocketHandler handler,
 			@Nullable String subProtocol, Supplier<HandshakeInfo> handshakeInfoFactory){