Apply Spring Boot's solution of coercing `false` LogLevel to `OFF`. (#575)

Fixes gh-556.

spring-cloud-context/src/main/java/org/springframework/cloud/logging/LoggingRebinder.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.logging;
 
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Map.Entry;
 
@@ -37,6 +38,7 @@ import org.springframework.core.env.Environment;
  * changed.
  *
  * @author Dave Syer
+ * @author Olga Maciaszek-Sharma
  *
  */
 public class LoggingRebinder
@@ -79,11 +81,19 @@ public class LoggingRebinder
 				name = null;
 			}
 			level = environment.resolvePlaceholders(level);
-			system.setLogLevel(name, LogLevel.valueOf(level.toUpperCase()));
+			system.setLogLevel(name, resolveLogLevel(level));
 		}
 		catch (RuntimeException ex) {
 			this.logger.error("Cannot set level: " + level + " for '" + name + "'");
 		}
 	}
 
+	private LogLevel resolveLogLevel(String level) {
+		String trimmedLevel = level.trim();
+		if ("false".equalsIgnoreCase(trimmedLevel)) {
+			return LogLevel.OFF;
+		}
+		return LogLevel.valueOf(trimmedLevel.toUpperCase(Locale.ENGLISH));
+	}
+
 }

spring-cloud-context/src/test/java/org/springframework/cloud/logging/LoggingRebinderTests.java

@@ -18,6 +18,7 @@ package org.springframework.cloud.logging;
 
 import java.util.Collections;
 
+import ch.qos.logback.classic.Level;
 import org.junit.After;
 import org.junit.Test;
 import org.slf4j.Logger;
@@ -33,6 +34,7 @@ import static org.assertj.core.api.BDDAssertions.then;
 
 /**
  * @author Dave Syer
+ * @author Olga Maciaszek-Sharma
  *
  */
 public class LoggingRebinderTests {
@@ -71,4 +73,17 @@ public class LoggingRebinderTests {
 		then(this.logger.isTraceEnabled()).isTrue();
 	}
 
+	@Test
+	public void logLevelFalseResolvedToOff() {
+		ch.qos.logback.classic.Logger logger = (ch.qos.logback.classic.Logger) LoggerFactory
+				.getLogger("org.springframework.cloud");
+		StandardEnvironment environment = new StandardEnvironment();
+		TestPropertyValues.of("logging.level.org.springframework.cloud=false")
+				.applyTo(environment);
+		rebinder.setEnvironment(environment);
+		rebinder.onApplicationEvent(new EnvironmentChangeEvent(environment,
+				Collections.singleton("logging.level.org.springframework.cloud")));
+		then(Level.OFF).isEqualTo((logger.getLevel()));
+	}
+
 }