private static boolean hasValidRackInformation(final KafkaStreamsState state) {
        if (!state.rackId().isPresent()) {
            LOG.error("KafkaStreams client {} doesn't have a rack id configured.", state.processId().id());
            return false;
        }
        return true;
    }
This function returns whether the current application state has the required rack information
to make assignment decisions with.

@param taskType the type of task that we are trying to validate rack information for.

@return whether rack-aware assignment decisions can be made for this application.
streams/src/main/java/org/apache/kafka/streams/processor/assignment/TaskAssignmentUtils.java