private function buildRevision()
 {
     if ($this->revision) {
         return;
     }
     $revision = new RevisionEntity();
     $moduleOptions = \ZF\Doctrine\Audit\Module::getModuleOptions();
     if ($moduleOptions->getUser()) {
         $revision->setUser($moduleOptions->getUser());
     }
     $comment = $moduleOptions->getAuditService()->getComment();
     $revision->setComment($comment);
     $this->revision = $revision;
 }