Adapt to WebClient's new exception wrapping

See spring-projects/spring-framework#23842
See gh-23170

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/error/DefaultErrorWebExceptionHandlerIntegrationTests.java

@@ -42,6 +42,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
+import org.springframework.test.web.reactive.server.HttpHandlerConnector.FailureAfterResponseCompletedException;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -303,7 +304,7 @@ class DefaultErrorWebExceptionHandlerIntegrationTests {
 			WebTestClient client = getWebClient(context);
 			assertThatExceptionOfType(RuntimeException.class)
 					.isThrownBy(() -> client.get().uri("/commit").exchange().expectStatus())
-					.withCauseInstanceOf(IllegalStateException.class)
+					.withCauseInstanceOf(FailureAfterResponseCompletedException.class)
 					.withMessageContaining("Error occurred after response was completed");
 		});
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java

@@ -32,7 +32,6 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 
 import javax.net.ssl.KeyManagerFactory;
-import javax.net.ssl.SSLException;
 
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;
@@ -72,6 +71,7 @@ import org.springframework.util.SocketUtils;
 import org.springframework.util.unit.DataSize;
 import org.springframework.web.reactive.function.BodyInserters;
 import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.reactive.function.client.WebClientRequestException;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
@@ -269,7 +269,7 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 		Mono<String> result = client.post().uri("/test").contentType(MediaType.TEXT_PLAIN)
 				.body(BodyInserters.fromValue("Hello World")).exchange()
 				.flatMap((response) -> response.bodyToMono(String.class));
-		StepVerifier.create(result).expectError(SSLException.class).verify(Duration.ofSeconds(10));
+		StepVerifier.create(result).expectError(WebClientRequestException.class).verify(Duration.ofSeconds(10));
 	}
 
 	protected WebClient.Builder getWebClient(int port) {