title: Sonar refuses to analize multimodule project
body: <p>I have upgraded from Sonar 5.3 to 6.2 and a project X is giving me some weird errors at the sonar stage of the jenkins job (altough build finishes as STABLE).</p>
  
  <p>The project is a standard multimodule maven java project.</p>
  
  <p>Entering the project dashboard a single message appears on screen: </p>
  
  <blockquote>
    <p>"No analysis has been performed since creation. The only available
    section is the configuration."</p>
  </blockquote>
  
  <p>But in the upper-right corner the red "FAILED" tag shows up. That leads to the Background tasks of the project and there is the failed task with this error log:</p>
  
  <blockquote>
    <p>The project "com.foo:bar-submodule-1" is already defined in SonarQube
    but not as a module of project "com.foo:bar". If you really want to
    stop directly analysing project "com.foo:bar-submodule-1", please
    first delete it from SonarQube and then relaunch the analysis of
    project "com.foo:bar"</p>
  </blockquote>
  
  <p>I do not want to delete the project and lose the historical data.</p>
  
  <p>So the question is: How can i add a project Y (that is a submodule of project X but Sonar does not recognize it) as a submodule of project X?</p>
  
  <p><strong>EDIT 1</strong></p>
  
  <p>The parent project is the only one that has been analyzed through jenkins jobs.</p>