title: can't be indexed twice - testSourceDirectory and sourceDirectory are same
body: <p>I have created performance test as a maven submodule to my main module. All the test classes are written under src/<strong>main</strong>/java and not src/<strong>test</strong>/java</p>
  
  <p>I am able to package the project as jar and run it to performance test my project.</p>
  
  <p>I wanted to execute <code>mvn test</code>. For <code>mvn test</code> to work I should have <code>&lt;testSourceDirectory&gt;</code> value set. As in this case I have my code in src/main/java I set this to :</p>
  
  <pre><code>&lt;testSourceDirectory&gt;src/main/java&lt;/testSourceDirectory&gt;
  </code></pre>
  
  <p>Now <code>mvn test</code> works.</p>
  
  <p>But the Problem is sonar build fails with error complaining: <code>can't be indexed twice</code>. Which is obvious as for my pom <code>testSourceDirectory</code> and <code>sourceDirectory</code> are same.</p>
  
  <pre><code>[ERROR] Failed to execute goal 
  org.codehaus.mojo:sonar-maven-plugin:2.5:sonar (default-cli) 
     on project Blah: File [relative=XYZ.java, abs=/Path/XYZ.java] can't be indexed twice. 
  Please check that inclusion/exclusion patterns produce 
  disjoint sets for main and test files -&gt; 
  </code></pre>
  
  <p>How to fix this issue?</p>