title: sonar-maven-plugin fails because of invalid checkstyle.xml (The processing instruction target matching "[xX][mM][lL]" is not allowed)
body: <p>I use Maven 3.2.1 and SonarQube 4.5 in conjunction with Checkstyle 5.6. Executing</p>
  
  <pre><code>mvn sonar:sonar
  </code></pre>
  
  <p>works fine for some projects, but others fail with "Can not execute Checkstyle: unable to read ... checkstyle.xml - unable to parse configuration stream - The processing instruction target matching "[xX][mM][lL]" is not allowed". Here's the output:</p>
  
  <pre><code>### ~\.mavenrc
  ### Set JAVA_HOME for maven to /opt/Oracle_Java/jdk1.7.0_67
  ### Set MAVEN_OPTS to -Xmx512m -XX:MaxPermSize=512m
  
  [INFO] Scanning for projects...
  [INFO] 
  [INFO] Using the builder    org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder with a thread count of 1
  [INFO]                                                                         
  [INFO] ------------------------------------------------------------------------
  [INFO] Building cc4-common 4.14.10-SNAPSHOT
  [INFO] ------------------------------------------------------------------------
  [INFO] 
  [INFO] --- sonar-maven-plugin:2.4:sonar (default-cli) @ cc4-common ---
  [INFO] SonarQube version: 4.5
  INFO: Default locale: "en_US", source code encoding: "UTF-8"
  INFO: Work directory: /srv/build/jenkins/jobs/cc4-trunk/workspace/trunk/cc4-   common/target/sonar
  INFO: SonarQube Server 4.5
  [INFO] [13:09:54.973] Load global referentials...
  [INFO] [13:09:55.122] Load global referentials done: 151 ms
  [INFO] [13:09:55.134] User cache: /var/lib/jenkins/.sonar/cache
  [INFO] [13:09:55.145] Install plugins
  [INFO] [13:09:55.268] Install JDBC driver
  [INFO] [13:09:55.278] Create JDBC datasource for jdbc:mysql://localhost:3306/sonar?   useUnicode=true&amp;characterEncoding=utf8&amp;rewriteBatchedStatements=true&amp;useConfigs=maxPerformance
  [INFO] [13:09:57.034] Initializing Hibernate
  [INFO] [13:09:58.837] Load project referentials...
  [INFO] [13:09:59.766] Load project referentials done: 929 ms
  [INFO] [13:09:59.766] Load project settings
  [INFO] [13:10:00.806] Loading technical debt model...
  [INFO] [13:10:00.838] Loading technical debt model done: 32 ms
  [INFO] [13:10:00.843] Apply project exclusions
  [INFO] [13:10:01.201] -------------  Scan cc4-common
  [INFO] [13:10:01.206] Load module settings
  [INFO] [13:10:02.293] Loading rules...
  [INFO] [13:10:02.888] Loading rules done: 595 ms
  [INFO] [13:10:02.907] Configure Maven plugins
  [INFO] [13:10:03.161] Compare to previous analysis (2014-10-06)
  [INFO] [13:10:03.217] Compare over 30 days (2014-09-13, analysis of 2014-09-13    02:44:12.0)
  [INFO] [13:10:03.237] Compare to previous version (2014-07-16)
  [INFO] [13:10:03.238] No quality gate is configured.
  [INFO] [13:10:03.366] Initializer FindbugsMavenInitializer...
  [INFO] [13:10:03.367] Initializer FindbugsMavenInitializer done: 1 ms
  [INFO] [13:10:03.367] Base dir: /srv/build/jenkins/jobs/cc4-trunk/workspace/trunk/cc4-   common
  [INFO] [13:10:03.367] Working dir: /srv/build/jenkins/jobs/cc4-trunk/workspace/trunk/cc4-common/target/sonar
  [INFO] [13:10:03.368] Source paths: pom.xml, src/main/java
  [INFO] [13:10:03.368] Test paths: src/test/java
  [INFO] [13:10:03.368] Binary dirs: target/classes
  [INFO] [13:10:03.368] Source encoding: UTF-8, default locale: en_US
  [INFO] [13:10:03.368] Index files
  [INFO] [13:10:03.378] Excluded sources: 
  [INFO] [13:10:03.378]   **/package-info.java
  [INFO] [13:10:04.074] 431 files indexed
  [INFO] [13:10:08.941] Quality profile for java: SE-Tools 3.2 (with Findbugs)
  [INFO] [13:10:09.281] Sensor JavaSquidSensor...
  [INFO] [13:10:09.429] Java Main Files AST scan...
  [INFO] [13:10:09.434] 273 source files to be analyzed
  [ERROR] [13:10:09.873] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:09.891] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:09.934] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:10.134] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:10.267] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:10.296] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:10.778] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.121] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.452] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.491] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:11.515] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:11.574] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.576] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:11.632] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.658] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.690] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:11.699] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:12.654] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:12.668] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:12.687] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:12.712] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:13.052] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.089] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.140] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.182] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.307] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.349] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.375] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.393] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:13.466] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:15.425] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:15.475] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:15.501] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:15.516] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:15.533] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:15.538] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:15.577] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:15.591] Class not found: org.apache.commons.logging.Log
  [ERROR] [13:10:15.604] Class not found: org.slf4j.impl.StaticLoggerBinder
  [ERROR] [13:10:15.613] Class not found: org.apache.commons.logging.Log
  [INFO] [13:10:15.615] 273/273 source files analyzed
  [INFO] [13:10:15.666] Java Main Files AST scan done: 6237 ms
  [INFO] [13:10:15.672] Java bytecode scan...
  [INFO] [13:10:16.374] Java bytecode scan done: 702 ms
  [INFO] [13:10:16.375] Java Test Files AST scan...
  [INFO] [13:10:16.375] 158 source files to be analyzed
  [INFO] [13:10:17.124] 158/158 source files analyzed
  [INFO] [13:10:17.124] Java Test Files AST scan done: 749 ms
  [INFO] [13:10:17.182] Package design analysis...
  [INFO] [13:10:17.414] Package design analysis done: 232 ms
  [INFO] [13:10:18.041] Sensor JavaSquidSensor done: 8759 ms
  [INFO] [13:10:18.045] Sensor QProfileSensor...
  [INFO] [13:10:18.049] Sensor QProfileSensor done: 4 ms
  [INFO] [13:10:18.049] Sensor FindbugsSensor...
  [INFO] [13:10:18.061] Execute Findbugs 3.0.0...
  [INFO] [13:10:19.885] Findbugs output report: /srv/build/jenkins/jobs/cc4-trunk/workspace/trunk/cc4-common/target/sonar/findbugs-result.xml
  [INFO] [13:10:41.963] Execute Findbugs 3.0.0 done: 23902 ms
  [INFO] [13:10:42.008] Sensor FindbugsSensor done: 23959 ms
  [INFO] [13:10:42.008] Sensor CheckstyleSensor...
  [INFO] [13:10:42.017] Execute Checkstyle 5.6...
  [INFO] [13:10:42.042] Checkstyle configuration: /srv/build/jenkins/jobs/cc4-trunk/workspace/trunk/cc4-common/target/sonar/checkstyle.xml
  [ERROR] Can not execute Checkstyle
  [INFO] ------------------------------------------------------------------------
  [INFO] BUILD FAILURE
  [INFO] ------------------------------------------------------------------------
  [INFO] Total time: 48.949 s
  [INFO] Finished at: 2014-10-13T13:10:42+01:00
  [INFO] Final Memory: 22M/286M
  [INFO] ------------------------------------------------------------------------
  [ERROR] Failed to execute goal org.codehaus.mojo:sonar-maven-plugin:2.4:sonar (default-cli) on project cc4-common: Can not execute Checkstyle: unable to read /srv/build/jenkins/jobs/cc4-trunk/workspace/trunk/cc4-common/target/sonar/checkstyle.xml - unable to parse configuration stream - The processing instruction target matching "[xX][mM][lL]" is not allowed.:1:223 -&gt; [Help 1]
  [ERROR] 
  [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
  [ERROR] Re-run Maven using the -X switch to enable full debug logging.
  [ERROR] 
  [ERROR] For more information about the errors and possible solutions, please read the following articles:
  [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
  </code></pre>
  
  <p>In fact, the generated checkstyle.xml is faulty because it contains "&lt;\?xml" and "&lt;\module" twice:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;&lt;!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.2//EN" "http://www.puppycrawl.com/dtds/configuration_1_2.dtd"&gt;&lt;!-- Generated by Sonar --&gt;&lt;module name="Checker"&gt;&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.3//EN" "http://www.puppycrawl.com/dtds/configuration_1_3.dtd"&gt;
  
  &lt;!--
      This configuration file was written by the eclipse-cs plugin configuration editor
  --&gt;
  &lt;!--
      Checkstyle-Configuration: CheckStyle configuration from the Maven parent
      Description: none
  --&gt;
  &lt;module name="Checker"&gt;
    &lt;property name="severity" value="warning"/&gt;
    &lt;module name="TreeWalker"&gt;
  ...
  </code></pre>
  
  <p>For analysis I uploaded this file:
   - checkstyle.xml: <a href="https://dl.dropboxusercontent.com/u/54665247/checkstyle.xml" rel="nofollow">https://dl.dropboxusercontent.com/u/54665247/checkstyle.xml</a></p>
  
  <p>Doing Google research I found nothing.
  Can anybody help me on this?</p>