Disable test that is flaky due to Reactor Netty problem

See gh-21437

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactoryTests.java

@@ -21,6 +21,7 @@ import java.time.Duration;
 import java.util.Arrays;
 
 import org.awaitility.Awaitility;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 import reactor.core.publisher.Mono;
@@ -125,6 +126,12 @@ class NettyReactiveWebServerFactoryTests extends AbstractReactiveWebServerFactor
 		this.webServer.stop();
 	}
 
+	@Disabled("Flaky due to https://github.com/reactor/reactor-netty/issues/1093")
+	@Override
+	protected void whenARequestRemainsInFlightThenShutDownGracefullyDoesNotInvokeCallbackUntilTheRequestCompletes() {
+
+	}
+
 	protected Mono<String> testSslWithAlias(String alias) {
 		String keyStore = "classpath:test.jks";
 		String keyPassword = "password";

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

@@ -359,7 +359,7 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 	}
 
 	@Test
-	void whenARequestRemainsInFlightThenShutDownGracefullyDoesNotInvokeCallbackUntilTheRequestCompletes()
+	protected void whenARequestRemainsInFlightThenShutDownGracefullyDoesNotInvokeCallbackUntilTheRequestCompletes()
 			throws Exception {
 		AbstractReactiveWebServerFactory factory = getFactory();
 		factory.setShutdown(Shutdown.GRACEFUL);