public Map.Entry<String, Long> pollExpiredConnection(long currentTimeNanos) {
            if (currentTimeNanos <= nextIdleCloseCheckTime)
                return null;

            if (lruConnections.isEmpty()) {
                nextIdleCloseCheckTime = currentTimeNanos + connectionsMaxIdleNanos;
                return null;
            }

            Map.Entry<String, Long> oldestConnectionEntry = lruConnections.entrySet().iterator().next();
            Long connectionLastActiveTime = oldestConnectionEntry.getValue();
            nextIdleCloseCheckTime = connectionLastActiveTime + connectionsMaxIdleNanos;

            if (currentTimeNanos > nextIdleCloseCheckTime)
                return oldestConnectionEntry;
            else
                return null;
        }
Close the channel now, regardless of whether the delay has expired or not.
clients/src/main/java/org/apache/kafka/common/network/Selector.java