Ensure non-remapped calls are still logged

Update LevelRemappingAppender to that any calls that aren't remapped
are still logged.

Fixes gh-1481

Author: philwebb

spring-boot/src/main/java/org/springframework/boot/logging/logback/LevelRemappingAppender.java

@@ -52,11 +52,9 @@ public class LevelRemappingAppender extends AppenderBase<ILoggingEvent> {
 
 	@Override
 	protected void append(ILoggingEvent event) {
-		Level remappedLevel = this.remapLevels.get(event.getLevel());
-		if (remappedLevel != null) {
-			AppendableLogger logger = getLogger(this.destinationLogger);
-			logger.callAppenders(new RemappedLoggingEvent(event));
-		}
+		AppendableLogger logger = getLogger(this.destinationLogger);
+		Level remapped = this.remapLevels.get(event.getLevel());
+		logger.callAppenders(remapped == null ? event : new RemappedLoggingEvent(event));
 	}
 
 	protected AppendableLogger getLogger(String name) {

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

@@ -86,6 +86,13 @@ public void customRemaps() throws Exception {
 		assertThat(this.logCaptor.getAllValues().get(1).getLevel(), equalTo(Level.WARN));
 	}
 
+	@Test
+	public void notRemapped() throws Exception {
+		this.appender.append(mockLogEvent(Level.TRACE));
+		verify(this.logger).callAppenders(this.logCaptor.capture());
+		assertThat(this.logCaptor.getAllValues().get(0).getLevel(), equalTo(Level.TRACE));
+	}
+
 	private ILoggingEvent mockLogEvent(Level level) {
 		ILoggingEvent event = mock(ILoggingEvent.class);
 		given(event.getLevel()).willReturn(level);