/**
  * Retrieve stacktrace from cause if set or from self otherwise.
  *
  * @return  lang.StackTraceElement[] array of stack trace elements
  * @see     xp://lang.StackTraceElement
  */
 public function getStackTrace()
 {
     if (null !== $this->cause) {
         return $this->cause->getStackTrace();
     }
     return parent::getStackTrace();
 }