Ensure that Cassandra's DriverConfigLoader is only closed once

Fixes gh-25796

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfiguration.java

@@ -104,7 +104,7 @@ public class CassandraAutoConfiguration {
 		}
 	}
 
-	@Bean
+	@Bean(destroyMethod = "")
 	@ConditionalOnMissingBean
 	public DriverConfigLoader cassandraDriverConfigLoader(CassandraProperties properties,
 			ObjectProvider<DriverConfigLoaderBuilderCustomizer> builderCustomizers) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/cassandra/CassandraAutoConfigurationIntegrationTests.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2012-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.cassandra;
+
+import java.time.Duration;
+
+import com.datastax.oss.driver.api.core.CqlSession;
+import com.datastax.oss.driver.api.core.config.DriverConfigLoader;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.CassandraContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.testsupport.testcontainers.DockerImageNames;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
+/**
+ * Integration tests for {@link CassandraAutoConfiguration}.
+ *
+ * @author Andy Wilkinson
+ */
+@Testcontainers(disabledWithoutDocker = true)
+class CassandraAutoConfigurationIntegrationTests {
+
+	@Container
+	static final CassandraContainer<?> cassandra = new CassandraContainer<>(DockerImageNames.cassandra())
+			.withStartupAttempts(5).withStartupTimeout(Duration.ofMinutes(10));
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+			.withConfiguration(AutoConfigurations.of(CassandraAutoConfiguration.class)).withPropertyValues(
+					"spring.data.cassandra.contact-points:" + cassandra.getHost() + ":"
+							+ cassandra.getFirstMappedPort(),
+					"spring.data.cassandra.local-datacenter=datacenter1", "spring.data.cassandra.request.timeout=20s",
+					"spring.data.cassandra.connection.init-query-timeout=10s");
+
+	@Test
+	void whenTheContextIsClosedThenTheDriverConfigLoaderIsClosed() {
+		this.contextRunner.withUserConfiguration(DriverConfigLoaderSpyConfiguration.class).run((context) -> {
+			assertThat(((BeanDefinitionRegistry) context.getSourceApplicationContext())
+					.getBeanDefinition("cassandraDriverConfigLoader").getDestroyMethodName()).isEmpty();
+			// Initialize lazy bean
+			context.getBean(CqlSession.class);
+			DriverConfigLoader driverConfigLoader = context.getBean(DriverConfigLoader.class);
+			context.close();
+			verify(driverConfigLoader).close();
+		});
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	static class DriverConfigLoaderSpyConfiguration {
+
+		@Bean
+		static BeanPostProcessor driverConfigLoaderSpy() {
+			return new BeanPostProcessor() {
+
+				@Override
+				public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
+					if (bean instanceof DriverConfigLoader) {
+						return spy(bean);
+					}
+					return bean;
+				}
+
+			};
+		}
+
+	}
+
+}