added Logback support

maven-embedder/pom.xml

@@ -74,6 +74,12 @@
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>
     </dependency>
+    <dependency>
+      <groupId>ch.qos.logback</groupId>
+      <artifactId>logback-classic</artifactId>
+      <version>1.0.7</version>
+      <optional>true</optional>
+    </dependency>      
     <!-- CLI -->
     <dependency>
       <groupId>commons-cli</groupId>

maven-embedder/src/main/java/org/apache/maven/cli/logging/impl/LogbackConfiguration.java

@@ -0,0 +1,62 @@
+package org.apache.maven.cli.logging.impl;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.io.File;
+
+import org.apache.maven.cli.logging.BaseSlf4jConfiguration;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Configuration for slf4j-logback.
+ * 
+ * @author Hervé Boutemy
+ */
+public class LogbackConfiguration
+    extends BaseSlf4jConfiguration
+{
+    @Override
+    public void setRootLoggerLevel( Level level )
+    {
+        ch.qos.logback.classic.Level value = ch.qos.logback.classic.Level.INFO;
+        switch ( level )
+        {
+            case DEBUG:
+                value = ch.qos.logback.classic.Level.DEBUG;
+                break;
+            
+            case INFO:
+                value = ch.qos.logback.classic.Level.INFO;
+                break;
+
+            case ERROR:
+                value = ch.qos.logback.classic.Level.ERROR;
+                break;
+        }
+        ( (ch.qos.logback.classic.Logger) LoggerFactory.getLogger( Logger.ROOT_LOGGER_NAME ) ).setLevel( value );
+    }
+
+    @Override
+    public void setLoggerFile( File output )
+    {
+        // no op
+    }
+}

maven-embedder/src/main/resources/META-INF/maven/slf4j-configuration.properties

@@ -2,3 +2,4 @@
 # value = corresponding o.a.m.cli.logging.Slf4jConfiguration class
 org.slf4j.impl.SimpleLoggerFactory org.apache.maven.cli.logging.impl.Slf4jSimpleConfiguration
 org.slf4j.helpers.Log4JLoggerFactory org.apache.maven.cli.logging.impl.Log4j2Configuration
+ch.qos.logback.classic.LoggerContext org.apache.maven.cli.logging.impl.LogbackConfiguration