Adapt to Logback deprecation

This commit also adds a test so that we can catch this problem hopefully
sooner in the future.

Closes gh-42006

Author: snicoll

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/logback/defaults.xml

@@ -5,11 +5,11 @@ Default logback configuration provided for import
 -->
 
 <included>
-	<conversionRule conversionWord="applicationName" converterClass="org.springframework.boot.logging.logback.ApplicationNameConverter" />
-	<conversionRule conversionWord="clr" converterClass="org.springframework.boot.logging.logback.ColorConverter" />
-	<conversionRule conversionWord="correlationId" converterClass="org.springframework.boot.logging.logback.CorrelationIdConverter" />
-	<conversionRule conversionWord="wex" converterClass="org.springframework.boot.logging.logback.WhitespaceThrowableProxyConverter" />
-	<conversionRule conversionWord="wEx" converterClass="org.springframework.boot.logging.logback.ExtendedWhitespaceThrowableProxyConverter" />
+	<conversionRule conversionWord="applicationName" class="org.springframework.boot.logging.logback.ApplicationNameConverter" />
+	<conversionRule conversionWord="clr" class="org.springframework.boot.logging.logback.ColorConverter" />
+	<conversionRule conversionWord="correlationId" class="org.springframework.boot.logging.logback.CorrelationIdConverter" />
+	<conversionRule conversionWord="wex" class="org.springframework.boot.logging.logback.WhitespaceThrowableProxyConverter" />
+	<conversionRule conversionWord="wEx" class="org.springframework.boot.logging.logback.ExtendedWhitespaceThrowableProxyConverter" />
 
 	<property name="CONSOLE_LOG_PATTERN" value="${CONSOLE_LOG_PATTERN:-%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr(%applicationName[%15.15t]){faint} %clr(${LOG_CORRELATION_PATTERN:-}){faint}%clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
 	<property name="CONSOLE_LOG_CHARSET" value="${CONSOLE_LOG_CHARSET:-${file.encoding:-UTF-8}}"/>

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

@@ -130,6 +130,22 @@ void cleanUp() {
 		((LoggerContext) LoggerFactory.getILoggerFactory()).stop();
 	}
 
+	@Test
+	void logbackDefaultsConfigurationDoesNotTriggerDeprecation(CapturedOutput output) {
+		initialize(this.initializationContext, "classpath:logback-include-defaults.xml", null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world")).isEqualTo("[INFO] - Hello world");
+		assertThat(output.toString()).doesNotContain("WARN").doesNotContain("deprecated");
+	}
+
+	@Test
+	void logbackBaseConfigurationDoesNotTriggerDeprecation(CapturedOutput output) {
+		initialize(this.initializationContext, "classpath:logback-include-base.xml", null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world")).contains(" INFO ").endsWith(": Hello world");
+		assertThat(output.toString()).doesNotContain("WARN").doesNotContain("deprecated");
+	}
+
 	@Test
 	@ClassPathOverrides({ "org.jboss.logging:jboss-logging:3.5.0.Final", "org.apache.logging.log4j:log4j-core:2.19.0" })
 	void jbossLoggingRoutesThroughLog4j2ByDefault() {

spring-boot-project/spring-boot/src/test/resources/logback-include-defaults.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+	<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
+	<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
+		<encoder>
+			<pattern>[%p] - %m%n</pattern>
+		</encoder>
+	</appender>
+	<root level="INFO">
+		<appender-ref ref="CONSOLE" />
+	</root>
+</configuration>