code: public synchronized boolean removeDriveListener(final IUSBDriveListener listener) {
          final boolean removed = listeners.remove(listener);
          if (listeners.isEmpty()) {
              stop();
          }
  
          return removed;
      }
docs: Removes an IUSBDriveListener.
  <p>
  The polling timer is automatically stopped if this is the last listener
  being removed.
  </p>
  
  @param listener the listener to remove
  @return true if the listener existed in the list and was successfully
  removed