Configure Flyway with initSqls for any DataSource configuration

Previously, spring.flyway.init-sqls was only applied to Flyway's
configuration if Flyway was being configured to create the DataSource.
If Flyway was being configured to use an existing DataSource, init-sqls
was not applied. This is a hangover from when the init SQLs support was
introduced. At that time, Flyway only supported SQL to initialize the
connection when it was creating the DataSource. Flyway 5.2 added init
SQL support no matter how Flyway's DataSource was configured.

This commit updates FlywayAutoConfiguration to always apply the
init-sqls property to Flyway's configuration. The property's
documentation does not describe the current limitation so this change
should align the behaviour with what the documentation leads people to
expect.

Fixes spring-projectsgh-23392

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/flyway/FlywayAutoConfiguration.java

@@ -145,10 +145,6 @@ private DataSource configureDataSource(FluentConfiguration configuration, Flyway
 				String user = getProperty(properties::getUser, dataSourceProperties::determineUsername);
 				String password = getProperty(properties::getPassword, dataSourceProperties::determinePassword);
 				configuration.dataSource(url, user, password);
-				if (!CollectionUtils.isEmpty(properties.getInitSqls())) {
-					String initSql = StringUtils.collectionToDelimitedString(properties.getInitSqls(), "\n");
-					configuration.initSql(initSql);
-				}
 			}
 			else if (flywayDataSource != null) {
 				configuration.dataSource(flywayDataSource);
@@ -206,6 +202,9 @@ private void configureProperties(FluentConfiguration configuration, FlywayProper
 			map.from(properties.isSkipDefaultCallbacks()).to(configuration::skipDefaultCallbacks);
 			map.from(properties.isSkipDefaultResolvers()).to(configuration::skipDefaultResolvers);
 			map.from(properties.isValidateOnMigrate()).to(configuration::validateOnMigrate);
+			map.from(properties.getInitSqls()).whenNot(CollectionUtils::isEmpty)
+					.as((initSqls) -> StringUtils.collectionToDelimitedString(initSqls, "\n"))
+					.to(configuration::initSql);
 			// Pro properties
 			map.from(properties.getBatch()).whenNonNull().to(configuration::batch);
 			map.from(properties.getDryRunOutput()).whenNonNull().to(configuration::dryRunOutput);

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/flyway/FlywayAutoConfigurationTests.java

@@ -502,6 +502,24 @@ void customFlywayClassLoader() {
 				});
 	}
 
+	@Test
+	void initSqlsWithDataSource() {
+		this.contextRunner.withUserConfiguration(EmbeddedDataSourceConfiguration.class)
+				.withPropertyValues("spring.flyway.init-sqls=SELECT 1").run((context) -> {
+					Flyway flyway = context.getBean(Flyway.class);
+					assertThat(flyway.getConfiguration().getInitSql()).isEqualTo("SELECT 1");
+				});
+	}
+
+	@Test
+	void initSqlsWithFlywayUrl() {
+		this.contextRunner.withPropertyValues("spring.flyway.url:jdbc:h2:mem:" + UUID.randomUUID(),
+				"spring.flyway.init-sqls=SELECT 1").run((context) -> {
+					Flyway flyway = context.getBean(Flyway.class);
+					assertThat(flyway.getConfiguration().getInitSql()).isEqualTo("SELECT 1");
+				});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class FlywayDataSourceConfiguration {