The solution is to change the line from:
PLUGINLIB_DECLARE_CLASS(router, RouterNode, RouterNode, nodelet::Nodelet);
to:
PLUGINLIB_EXPORT_CLASS(RouterNode, nodelet::Nodelet);
The solution is to change the line from:
PLUGINLIB_DECLARE_CLASS(router, RouterNode, RouterNode, nodelet::Nodelet);
to:
PLUGINLIB_EXPORT_CLASS(RouterNode, nodelet::Nodelet);