code: public boolean shouldRetryFor(Class<E> candidate) {
      Preconditions.checkNotNull(candidate, "Requires a non-null candidate class");
      if (dontRetry != null) {
        return !dontRetry.contains(candidate);
      } else {
        return true;
      }
    }
docs: Determines if a given class is an exception or error that this FailoverPolicy supports retry for.
  This is a supplement to the explicit behavior defined in {@link me.prettyprint.cassandra.connection.HConnectionManager}.