Polish "Downcast to InetSocketAddress for Jetty 10"

This commit uses the target type where getRemoteAddress and
getLocalAddress are defined.

See spring-projectsgh-27120

spring-websocket/src/main/java/org/springframework/web/socket/adapter/jetty/JettyWebSocketSession.java

@@ -306,7 +306,7 @@ private static class Jetty10SessionHelper implements SessionHelper {
 
 		static {
 			try {
-				Class<?> type = loader.loadClass("org.eclipse.jetty.websocket.api.WebSocketPolicy");
+				Class<?> type = loader.loadClass("org.eclipse.jetty.websocket.api.Session");
 				getTextMessageSizeLimitMethod = type.getMethod("getMaxTextMessageSize");
 				getBinaryMessageSizeLimitMethod = type.getMethod("getMaxBinaryMessageSize");
 				getRemoteAddressMethod = type.getMethod("getRemoteAddress");