Restore commons-logging dependency for spring-boot

Restore the dependency on commons-logging (transitively via spring-core)
for spring-boot. This means that we are not tied directly to SLF4J, but
it is still an option that can be used via `jcl-over-slf4j`.

The `spring-boot-starter-parent` continues to replace `commons-logging`
with `jcl-over-slf4j`.

Fixes gh-981

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/logging/AutoConfigurationReportLoggingInitializerTests.java

@@ -16,15 +16,14 @@
 
 package org.springframework.boot.autoconfigure.logging;
 
-import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogConfigurationException;
 import org.apache.commons.logging.LogFactory;
+import org.apache.commons.logging.impl.LogFactoryImpl;
 import org.apache.commons.logging.impl.NoOpLog;
-import org.apache.commons.logging.impl.SLF4JLogFactory;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -42,7 +41,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.event.ContextRefreshedEvent;
 import org.springframework.mock.web.MockServletContext;
-import org.springframework.util.ReflectionUtils;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 
 import static org.hamcrest.Matchers.containsString;
@@ -73,10 +71,6 @@ public class AutoConfigurationReportLoggingInitializerTests {
 
 	protected List<String> infoLog = new ArrayList<String>();
 
-	private Field logFactoryField;
-
-	private LogFactory originalLogFactory;
-
 	@Before
 	public void setup() {
 		setupLogging(true, true);
@@ -104,25 +98,15 @@ public class AutoConfigurationReportLoggingInitializerTests {
 			}
 		}).given(this.log).info(anyObject());
 
-		try {
+		LogFactory.releaseAll();
-			this.logFactoryField = LogFactory.class.getDeclaredField("logFactory");
+		System.setProperty(LogFactory.FACTORY_PROPERTY, MockLogFactory.class.getName());
-			ReflectionUtils.makeAccessible(this.logFactoryField);
-
-			this.originalLogFactory = (LogFactory) ReflectionUtils.getField(
-					this.logFactoryField, null);
-
-			ReflectionUtils.setField(this.logFactoryField, null, new MockLogFactory());
-		}
-		catch (Exception ex) {
-			throw new IllegalStateException("Failed to set logFactory", ex);
-		}
-
 		this.initializer = new AutoConfigurationReportLoggingInitializer();
 	}
 
 	@After
 	public void cleanup() {
-		ReflectionUtils.setField(this.logFactoryField, null, this.originalLogFactory);
+		System.clearProperty(LogFactory.FACTORY_PROPERTIES);
+		LogFactory.releaseAll();
 	}
 
 	@Test
@@ -215,7 +199,7 @@ public class AutoConfigurationReportLoggingInitializerTests {
 				containsString("Unable to provide auto-configuration report"));
 	}
 
-	public static class MockLogFactory extends SLF4JLogFactory {
+	public static class MockLogFactory extends LogFactoryImpl {
 		@Override
 		public Log getInstance(String name) throws LogConfigurationException {
 			if (AutoConfigurationReportLoggingInitializer.class.getName().equals(name)) {

spring-boot-cli/pom.xml

@@ -104,22 +104,17 @@
 		<dependency>
 			<groupId>org.eclipse.aether</groupId>
 			<artifactId>aether-transport-http</artifactId>
+			<exclusions>
+				<exclusion>
+					<artifactId>jcl-over-slf4j</artifactId>
+					<groupId>org.slf4j</groupId>
+				</exclusion>
+			</exclusions>
 		</dependency>
 		<dependency>
 			<groupId>org.eclipse.aether</groupId>
 			<artifactId>aether-util</artifactId>
 		</dependency>
-		<dependency>
-			<groupId>org.slf4j</groupId>
-			<artifactId>jcl-over-slf4j</artifactId>
-		</dependency>
-		<!-- Runtime -->
-		<dependency>
-			<groupId>org.slf4j</groupId>
-			<artifactId>slf4j-nop</artifactId>
-			<version>1.7.7</version>
-			<scope>runtime</scope>
-		</dependency>
 		<!-- Provided -->
 		<dependency>
 			<groupId>org.codehaus.groovy</groupId>

spring-boot-dependencies/pom.xml

@@ -429,6 +429,12 @@
 				<groupId>org.apache.httpcomponents</groupId>
 				<artifactId>httpasyncclient</artifactId>
 				<version>${httpasyncclient.version}</version>
+				<exclusions>
+					<exclusion>
+						<groupId>commons-logging</groupId>
+						<artifactId>commons-logging</artifactId>
+					</exclusion>
+				</exclusions>
 			</dependency>
 			<dependency>
 				<groupId>org.apache.tomcat.embed</groupId>
@@ -825,12 +831,6 @@
 				<groupId>org.springframework</groupId>
 				<artifactId>spring-core</artifactId>
 				<version>${spring.version}</version>
-				<exclusions>
-					<exclusion>
-						<groupId>commons-logging</groupId>
-						<artifactId>commons-logging</artifactId>
-					</exclusion>
-				</exclusions>
 			</dependency>
 			<dependency>
 				<groupId>org.springframework</groupId>

spring-boot-parent/pom.xml

@@ -367,15 +367,10 @@
 						<configuration>
 							<rules>
 								<requireJavaVersion>
-									<version>1.7</version>
+									<version>(1.7,)</version>
 								</requireJavaVersion>
-								<bannedDependencies>
-									<excludes>
-										<exclude>commons-logging:commons-logging:*:compile</exclude>
-									</excludes>
-									<searchTransitive>true</searchTransitive>
-								</bannedDependencies>
 							</rules>
+							<fail>true</fail>
 						</configuration>
 					</execution>
 				</executions>

spring-boot-tools/spring-boot-loader-tools/.gitignore

@@ -0,0 +1 @@
+/target

spring-boot/pom.xml

@@ -20,10 +20,6 @@
 	</properties>
 	<dependencies>
 		<!-- Compile -->
-		<dependency>
-			<groupId>org.slf4j</groupId>
-			<artifactId>jcl-over-slf4j</artifactId>
-		</dependency>
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-core</artifactId>
@@ -154,6 +150,11 @@
 			<artifactId>spring-webmvc</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>jcl-over-slf4j</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 	<build>
 		<plugins>