return null;
}
} else if (taskObject instanceof Callable) {
this.schedule((Callable) taskObject, scheduled, delay, unit);
} else {
logger.warning(String.format(
"[%s] Invalid service instance. Only Runnable or Callable " +
"objects are allowed.\n" +
"Service '%s' of class '%s' has not been activated " +
"in '%s' mode.",
this.getClass().getSimpleName(),