Ensure that building the SNI test apps produces Java 17 bytecode

See gh-41980

spring-boot-tests/spring-boot-integration-tests/spring-boot-sni-tests/spring-boot-sni-client-app/build.gradle

@@ -5,6 +5,11 @@ plugins {
 
 apply plugin: "io.spring.dependency-management"
 
+java {
+	sourceCompatibility = '17'
+	targetCompatibility = '17'
+}
+
 repositories {
 	maven { url "file:${rootDir}/../int-test-maven-repository"}
 	mavenCentral()

spring-boot-tests/spring-boot-integration-tests/spring-boot-sni-tests/spring-boot-sni-reactive-app/build.gradle

@@ -2,11 +2,16 @@ import org.springframework.boot.gradle.tasks.bundling.BootJar
 
 plugins {
 	id "java"
-	id "org.springframework.boot" version "3.3.0-SNAPSHOT"
+	id "org.springframework.boot"
 }
 
 apply plugin: "io.spring.dependency-management"
 
+java {
+	sourceCompatibility = '17'
+	targetCompatibility = '17'
+}
+
 repositories {
 	maven { url "file:${rootDir}/../int-test-maven-repository"}
 	mavenCentral()

spring-boot-tests/spring-boot-integration-tests/spring-boot-sni-tests/spring-boot-sni-servlet-app/build.gradle

@@ -2,11 +2,16 @@ import org.springframework.boot.gradle.tasks.bundling.BootJar
 
 plugins {
 	id "java"
-	id "org.springframework.boot" version "3.3.0-SNAPSHOT"
+	id "org.springframework.boot"
 }
 
 apply plugin: "io.spring.dependency-management"
 
+java {
+	sourceCompatibility = '17'
+	targetCompatibility = '17'
+}
+
 repositories {
 	maven { url "file:${rootDir}/../int-test-maven-repository"}
 	mavenCentral()

spring-boot-tests/spring-boot-integration-tests/spring-boot-sni-tests/src/intTest/java/org/springframework/boot/sni/SniIntegrationTests.java

@@ -21,6 +21,7 @@ import java.time.Duration;
 import java.util.Map;
 
 import org.awaitility.Awaitility;
+import org.awaitility.core.ConditionTimeoutException;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
 import org.testcontainers.containers.GenericContainer;
@@ -56,7 +57,13 @@ class SniIntegrationTests {
 	void home(String webStack, String server) {
 		try (ApplicationContainer serverContainer = new ServerApplicationContainer(webStack, server)) {
 			serverContainer.start();
-			Awaitility.await().atMost(Duration.ofSeconds(60)).until(serverContainer::isRunning);
+			try {
+				Awaitility.await().atMost(Duration.ofSeconds(60)).until(serverContainer::isRunning);
+			}
+			catch (ConditionTimeoutException ex) {
+				System.out.println(serverContainer.getLogs());
+				throw ex;
+			}
 			String serverLogs = serverContainer.getLogs();
 			assertThat(serverLogs).contains(SERVER_START_MESSAGES.get(server));
 			try (ApplicationContainer clientContainer = new ClientApplicationContainer()) {