Upgrade to Log4j2 2.20.0

Closes gh-34349

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -776,7 +776,7 @@ bom {
 			]
 		}
 	}
-	library("Log4j2", "2.19.0") {
+	library("Log4j2", "2.20.0") {
 		group("org.apache.logging.log4j") {
 			imports = [
 				"log4j-bom"

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystemTests.java

@@ -402,8 +402,7 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 		LoggerContext loggerContext = (LoggerContext) LogManager.getContext(false);
 		this.loggingSystem.beforeInitialize();
 		this.loggingSystem.initialize(this.initializationContext, null, null);
-		loggerContext.getConfiguration()
-			.addLogger("com.example.test",
+		loggerContext.getConfiguration().addLogger("com.example.test",
 				new LoggerConfig("com.example.test", org.apache.logging.log4j.Level.INFO, false));
 		this.loggingSystem.setLogLevel("com.example", LogLevel.WARN);
 		this.loggingSystem.setLogLevel("com.example.test", LogLevel.DEBUG);
@@ -427,6 +426,7 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 
 		this.loggingSystem.initialize(this.initializationContext, null, null);
 		java.util.logging.Logger logger = java.util.logging.Logger.getLogger(Log4J2LoggingSystemTests.class.getName());
+		logger.info("Log to trigger level propagation");
 		assertThat(logger.getLevel()).isNull();
 		this.loggingSystem.setLogLevel(Log4J2LoggingSystemTests.class.getName(), LogLevel.DEBUG);
 		assertThat(logger.getLevel()).isEqualTo(Level.FINE);
@@ -477,9 +477,7 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 		assertThatIllegalStateException()
 				.isThrownBy(() -> this.loggingSystem.initialize(this.initializationContext,
 						"http://localhost:8080/shouldnotwork", null))
-			.havingCause()
-			.isInstanceOf(ProtocolException.class)
-			.withMessageContaining("http has not been enabled");
+				.havingCause().isInstanceOf(ProtocolException.class).withMessageContaining("http has not been enabled");
 	}
 
 	private String getRelativeClasspathLocation(String fileName) {