Allow flyway loggers to be configured and provide SLF4J default

Add `spring.flyway.loggers` property which can be used to configure
Flyway loggers and has a default value of "slf4j".

Closes gh-35158

Author: philwebb

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

@@ -245,6 +245,8 @@ private void configureProperties(FluentConfiguration configuration, FlywayProper
 				.to((prefix) -> configuration.scriptPlaceholderPrefix(prefix));
 			map.from(properties.getScriptPlaceholderSuffix())
 				.to((suffix) -> configuration.scriptPlaceholderSuffix(suffix));
+			map.from(properties.isExecuteInTransaction()).to(configuration::executeInTransaction);
+			map.from(properties::getLoggers).to(configuration::loggers);
 			// Flyway Teams properties
 			map.from(properties.getBatch()).to(configuration::batch);
 			map.from(properties.getDryRunOutput()).to(configuration::dryRunOutput);
@@ -269,7 +271,6 @@ private void configureProperties(FluentConfiguration configuration, FlywayProper
 				.as((patterns) -> patterns.toArray(new String[0]))
 				.to(configuration::ignoreMigrationPatterns);
 			map.from(properties.getDetectEncoding()).to(configuration::detectEncoding);
-			map.from(properties.isExecuteInTransaction()).to(configuration::executeInTransaction);
 		}
 
 		private void configureSqlServerKerberosLoginFile(FluentConfiguration configuration,

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

@@ -367,6 +367,11 @@ public class FlywayProperties {
 	 */
 	private boolean executeInTransaction = true;
 
+	/**
+	 * Loggers Flyway should use.
+	 */
+	private String[] loggers = { "slf4j" };
+
 	public boolean isEnabled() {
 		return this.enabled;
 	}
@@ -855,4 +860,12 @@ public void setExecuteInTransaction(boolean executeInTransaction) {
 		this.executeInTransaction = executeInTransaction;
 	}
 
+	public String[] getLoggers() {
+		return this.loggers;
+	}
+
+	public void setLoggers(String[] loggers) {
+		this.loggers = loggers;
+	}
+
 }

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

@@ -763,6 +763,21 @@ void containsResourceProviderCustomizer() {
 			.run((context) -> assertThat(context).hasSingleBean(ResourceProviderCustomizer.class));
 	}
 
+	@Test
+	void loggers() {
+		this.contextRunner.withUserConfiguration(EmbeddedDataSourceConfiguration.class)
+			.run((context) -> assertThat(context.getBean(Flyway.class).getConfiguration().getLoggers())
+				.containsExactly("slf4j"));
+	}
+
+	@Test
+	void overrideLoggers() {
+		this.contextRunner.withUserConfiguration(EmbeddedDataSourceConfiguration.class)
+			.withPropertyValues("spring.flyway.loggers=log4j2")
+			.run((context) -> assertThat(context.getBean(Flyway.class).getConfiguration().getLoggers())
+				.containsExactly("log4j2"));
+	}
+
 	@Test
 	void shouldRegisterResourceHints() {
 		RuntimeHints runtimeHints = new RuntimeHints();