public long throttleDelayMs(String id, long now) {
        NodeConnectionState state = nodeState.get(id);
        if (state != null && state.throttleUntilTimeMs > now) {
            return state.throttleUntilTimeMs - now;
        } else {
            return 0;
        }
    }
Return the remaining throttling delay in milliseconds if throttling is in progress. Return 0, otherwise.
@param id the connection to check
@param now the current time in ms
clients/src/main/java/org/apache/kafka/clients/ClusterConnectionStates.java