Polish "Fix scope of CqlSessionBuilder bean"

See gh-19899

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

@@ -45,13 +45,13 @@ class CassandraAutoConfigurationTests {
 			.withConfiguration(AutoConfigurations.of(CassandraAutoConfiguration.class));
 
 	@Test
-	void cqlSessionBuilderThreadSafe() {
+	void cqlSessionBuildHasScopePrototype() {
 		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);
+			CqlSessionBuilder firstBuilder = context.getBean(CqlSessionBuilder.class);
+			assertThat(firstBuilder.withKeyspace(keyspace)).hasFieldOrPropertyWithValue("keyspace", keyspace);
+			CqlSessionBuilder secondBuilder = context.getBean(CqlSessionBuilder.class);
+			assertThat(secondBuilder).hasFieldOrPropertyWithValue("keyspace", null);
 		});
 	}
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -4266,6 +4266,8 @@ Generally, you provide `keyspace-name` and `contact-points` as well the local da
 You can also register an arbitrary number of beans that implement `DriverConfigLoaderBuilderCustomizer` for more advanced driver customizations.
 The `CqlSession` can be customized with a bean of type `CqlSessionBuilderCustomizer`.
 
+NOTE: If you're using `CqlSessionBuilder` to create multiple `CqlSession` beans, keep in mind the builder is mutable so make sure to inject a fresh copy for each session.
+
 The following code listing shows how to inject a Cassandra bean:
 
 [source,java,indent=0]