Polish "Avoid NPE in SimpleDataSourceProperties when driver is null"

See gh-45976

Author: snicoll

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/jdbc/DataSourceBuilder.java

@@ -709,7 +709,7 @@ private static class SimpleDataSourceProperties extends MappedDataSourceProperti
 		SimpleDataSourceProperties() {
 			add(DataSourceProperty.URL, SimpleDriverDataSource::getUrl, SimpleDriverDataSource::setUrl);
 			add(DataSourceProperty.DRIVER_CLASS_NAME, Class.class,
-					(dataSource) -> dataSource.getDriver() == null ? null : dataSource.getDriver().getClass(),
+					(dataSource) -> (dataSource.getDriver() != null) ? dataSource.getDriver().getClass() : null,
 					SimpleDriverDataSource::setDriverClass);
 			add(DataSourceProperty.USERNAME, SimpleDriverDataSource::getUsername, SimpleDriverDataSource::setUsername);
 			add(DataSourceProperty.PASSWORD, SimpleDriverDataSource::getPassword, SimpleDriverDataSource::setPassword);

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/jdbc/DataSourceBuilderTests.java

@@ -358,7 +358,7 @@ void buildWhenDerivedFromOracleUcpWithPasswordNotSetThrowsException() throws Exc
 	}
 
 	@Test
-	void buildWhenDerivedFromSimpleDriverDataSourceWithDriverNotSetSucceeds() throws Exception {
+	void buildWhenDerivedFromSimpleDriverDataSourceAndDriverNotSetBuilds() {
 		SimpleDriverDataSource dataSource = new SimpleDriverDataSource();
 		dataSource.setUsername("test");
 		dataSource.setPassword("secret");