Fix scope of CqlSessionBuilder bean

See gh-19899

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

@@ -44,6 +44,7 @@ import org.springframework.boot.context.properties.PropertyMapper;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Lazy;
+import org.springframework.context.annotation.Scope;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Cassandra.
@@ -69,6 +70,7 @@ public class CassandraAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
+	@Scope("prototype")
 	public CqlSessionBuilder cassandraSessionBuilder(CassandraProperties properties,
 			DriverConfigLoader driverConfigLoader, ObjectProvider<CqlSessionBuilderCustomizer> builderCustomizers) {
 		CqlSessionBuilder builder = CqlSession.builder().withConfigLoader(driverConfigLoader);

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

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.cassandra;
 
+import com.datastax.oss.driver.api.core.CqlIdentifier;
+import com.datastax.oss.driver.api.core.CqlSessionBuilder;
 import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
 import com.datastax.oss.driver.api.core.config.DriverConfigLoader;
 import com.datastax.oss.driver.api.core.config.DriverExecutionProfile;
@@ -42,6 +44,17 @@ class CassandraAutoConfigurationTests {
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(CassandraAutoConfiguration.class));
 
+	@Test
+	void cqlSessionBuilderThreadSafe() {
+		this.contextRunner.run((context) -> {
+			CqlIdentifier keyspace = CqlIdentifier.fromCql("test");
+			assertThat(context).hasSingleBean(CqlSessionBuilder.class);
+			assertThat(context.getBean(CqlSessionBuilder.class).withKeyspace(keyspace))
+					.hasFieldOrPropertyWithValue("keyspace", keyspace);
+			assertThat(context.getBean(CqlSessionBuilder.class)).hasFieldOrPropertyWithValue("keyspace", null);
+		});
+	}
+
 	@Test
 	void driverConfigLoaderWithDefaultConfiguration() {
 		this.contextRunner.run((context) -> {