Polish "Trim whitespace when coercing to a LogLevel"

Closes gh-15143

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

@@ -364,18 +364,19 @@ public class LoggingApplicationListener implements GenericApplicationListener {
 	private void setLogLevel(LoggingSystem system, String name, String level) {
 		try {
 			name = name.equalsIgnoreCase(LoggingSystem.ROOT_LOGGER_NAME) ? null : name;
-			system.setLogLevel(name, coerceLogLevel(level.trim()));
+			system.setLogLevel(name, coerceLogLevel(level));
 		}
 		catch (RuntimeException ex) {
-			this.logger.error("Cannot set level: " + level + " for '" + name + "'");
+			this.logger.error("Cannot set level '" + level + "' for '" + name + "'");
 		}
 	}
 
 	private LogLevel coerceLogLevel(String level) {
-		if ("false".equalsIgnoreCase(level)) {
+		String trimmedLevel = level.trim();
+		if ("false".equalsIgnoreCase(trimmedLevel)) {
 			return LogLevel.OFF;
 		}
-		return LogLevel.valueOf(level.toUpperCase(Locale.ENGLISH));
+		return LogLevel.valueOf(trimmedLevel.toUpperCase(Locale.ENGLISH));
 	}
 
 	private void registerShutdownHookIfNecessary(Environment environment,

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

@@ -318,6 +318,18 @@ public class LoggingApplicationListenerTests {
 		assertThat(this.outputCapture.toString()).contains("testattrace");
 	}
 
+	@Test
+	public void parseLevelsTrimsWhitespace() {
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context,
+				"logging.level.org.springframework.boot= trace ");
+		this.initializer.initialize(this.context.getEnvironment(),
+				this.context.getClassLoader());
+		this.logger.debug("testatdebug");
+		this.logger.trace("testattrace");
+		assertThat(this.outputCapture.toString()).contains("testatdebug");
+		assertThat(this.outputCapture.toString()).contains("testattrace");
+	}
+
 	@Test
 	public void parseLevelsWithPlaceholder() {
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.context,
@@ -338,7 +350,7 @@ public class LoggingApplicationListenerTests {
 				this.context.getClassLoader());
 		this.logger.debug("testatdebug");
 		assertThat(this.outputCapture.toString()).doesNotContain("testatdebug")
-				.contains("Cannot set level: GARBAGE");
+				.contains("Cannot set level 'GARBAGE'");
 	}
 
 	@Test