code: private static void checkNodesExistence(Model mo, Collection<Node> ns) throws SchedulerModelingException {
          for (Node node : ns) {
              if (!mo.getMapping().contains(node)) {
                  throw new SchedulerModelingException(mo, "Unknown node '" + node + "'");
              }
          }
      }
docs: Check for the existence of nodes in a model
  
  @param mo the model to check
  @param ns the nodes to check
  @throws SchedulerModelingException if at least one of the given nodes is not in the RP.