Polish logging listeners.

Rename slf4j package to log.
Shorten enabled properties.
JsonLogSpanListener only depends on Commons Logging.

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/log/JsonLogSpanListener.java

@@ -14,33 +14,33 @@
  * limitations under the License.
  */
 
-package org.springframework.cloud.sleuth.slf4j;
+package org.springframework.cloud.sleuth.log;
 
-import com.fasterxml.jackson.databind.DeserializationFeature;
 import lombok.Data;
 import lombok.SneakyThrows;
-import lombok.extern.slf4j.Slf4j;
+import lombok.extern.apachecommons.CommonsLog;
 
 import org.springframework.cloud.sleuth.event.SpanStoppedEvent;
 import org.springframework.context.event.EventListener;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 
+import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 /**
  * @author Spencer Gibb
  */
-@Slf4j
+@CommonsLog
 @Order(Ordered.LOWEST_PRECEDENCE)
 @Data
-public class JsonSlf4jSpanListener {
+public class JsonLogSpanListener {
 
 	private final String prefix;
 	private final String suffix;
 	private final ObjectMapper objectMapper = new ObjectMapper();
 
-	public JsonSlf4jSpanListener() {
+	public JsonLogSpanListener() {
 		prefix = "[span]";
 		suffix = "[endspan]";
 		objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
@@ -49,8 +49,7 @@ public class JsonSlf4jSpanListener {
 	@SneakyThrows
 	@EventListener(SpanStoppedEvent.class)
 	public void stop(SpanStoppedEvent event) {
-		log.info("{}{}{}", prefix,
-				objectMapper.writeValueAsString(event.getSpan()),
+		log.info(prefix + objectMapper.writeValueAsString(event.getSpan()) +
 				suffix);
 	}
 

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/log/SleuthLogAutoConfiguration.java

@@ -14,8 +14,9 @@
  * limitations under the License.
  */
 
-package org.springframework.cloud.sleuth.slf4j;
+package org.springframework.cloud.sleuth.log;
 
+import org.apache.commons.logging.Log;
 import org.slf4j.MDC;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
@@ -26,19 +27,26 @@ import org.springframework.context.annotation.Configuration;
  * @author Spencer Gibb
  */
 @Configuration
-@ConditionalOnClass(MDC.class)
-public class SleuthSlf4jAutoConfiguration {
+public class SleuthLogAutoConfiguration {
 
-	@Bean
-	@ConditionalOnProperty(value = "spring.cloud.sleuth.listener.slf4j.enabled", matchIfMissing = true)
-	public Slf4jSpanListener slf4jSpanStartedListener() {
-		return new Slf4jSpanListener();
+	@Configuration
+	@ConditionalOnClass(MDC.class)
+	protected static class Slf4jConfiguration {
+		@Bean
+		@ConditionalOnProperty(value = "spring.cloud.sleuth.log.slf4j.enabled", matchIfMissing = true)
+		public Slf4jSpanListener slf4jSpanStartedListener() {
+			return new Slf4jSpanListener();
+		}
 	}
 
-	@Bean
-	@ConditionalOnProperty("spring.cloud.sleuth.listener.json.slf4j.enabled")
-	public JsonSlf4jSpanListener jsonSlf4jSpanListener() {
-		return new JsonSlf4jSpanListener();
+	@Configuration
+	@ConditionalOnClass(Log.class)
+	protected static class JsonConfiguration {
+		@Bean
+		@ConditionalOnProperty("spring.cloud.sleuth.log.json.enabled")
+		public JsonLogSpanListener jsonSlf4jSpanListener() {
+			return new JsonLogSpanListener();
+		}
 	}
 
 }

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/log/Slf4jSpanListener.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.cloud.sleuth.slf4j;
+package org.springframework.cloud.sleuth.log;
 
 import static org.springframework.cloud.sleuth.Trace.SPAN_ID_NAME;
 import static org.springframework.cloud.sleuth.Trace.TRACE_ID_NAME;

spring-cloud-sleuth-core/src/main/resources/META-INF/spring.factories

@@ -1,7 +1,7 @@
 # Auto Configuration
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
 org.springframework.cloud.sleuth.autoconfig.TraceAutoConfiguration,\
-org.springframework.cloud.sleuth.slf4j.SleuthSlf4jAutoConfiguration,\
+org.springframework.cloud.sleuth.log.SleuthLogAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.scheduling.TraceSchedulingAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.web.TraceWebAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.web.client.TraceWebClientAutoConfiguration

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/log/JsonLogSpanListenerTests.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.cloud.sleuth.slf4j;
+package org.springframework.cloud.sleuth.log;
 
 import static org.junit.Assert.*;
 
@@ -30,13 +30,13 @@ import java.io.IOException;
 /**
  * @author Spencer Gibb
  */
-public class JsonSlf4jSpanListenerTests {
+public class JsonLogSpanListenerTests {
 	@Rule
 	public final OutputCapture output = new OutputCapture();
 
 	@Test
 	public void jsonSpanIsOnOneLine() throws IOException {
-		JsonSlf4jSpanListener listener = new JsonSlf4jSpanListener();
+		JsonLogSpanListener listener = new JsonLogSpanListener();
 		Span span = MilliSpan.builder()
 				.name("testSpan")
 				.spanId("spanId1")