Trim trailing whitespace from value of logging.config

Closes gh-22078

Author: mbhave

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/logging/LoggingApplicationListener.java

@@ -301,7 +301,7 @@ private boolean isSet(ConfigurableEnvironment environment, String property) {
 
 	private void initializeSystem(ConfigurableEnvironment environment, LoggingSystem system, LogFile logFile) {
 		LoggingInitializationContext initializationContext = new LoggingInitializationContext(environment);
-		String logConfig = environment.getProperty(CONFIG_PROPERTY);
+		String logConfig = StringUtils.trimWhitespace(environment.getProperty(CONFIG_PROPERTY));
 		if (ignoreLogConfig(logConfig)) {
 			system.initialize(initializationContext, null, logFile);
 		}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java

@@ -160,6 +160,14 @@ void overrideConfigLocation() {
 		assertThat(this.output).contains("Hello world").doesNotContain("???").startsWith("null ").endsWith("BOOTBOOT");
 	}
 
+	@Test
+	void trailingWhitespaceInLoggingConfigShouldBeTrimmed() {
+		addPropertiesToEnvironment(this.context, "logging.config=classpath:logback-nondefault.xml ");
+		this.initializer.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.logger.info("Hello world");
+		assertThat(this.output).contains("Hello world").doesNotContain("???").startsWith("null ").endsWith("BOOTBOOT");
+	}
+
 	@Test
 	void overrideConfigDoesNotExist() {
 		addPropertiesToEnvironment(this.context, "logging.config=doesnotexist.xml");