public synchronized boolean tryEvict(long now) {
        // Try to evict an entry which is stale.
        Map.Entry<LastUsedKey, ShareSession> lastUsedEntry = lastUsed.firstEntry();
        if (lastUsedEntry == null) {
            return false;
        } else if (now - lastUsedEntry.getKey().lastUsedMs() > evictionMs) {
            ShareSession session = lastUsedEntry.getValue();
            remove(session);
            return true;
        }
        return false;
    }
Try to evict an entry from the session cache.
<p>
A proposed new element A may evict an existing element B if:
B is considered "stale" because it has been inactive for a long time.

@param now        The current time in milliseconds.
@return           True if an entry was evicted; false otherwise.
server/src/main/java/org/apache/kafka/server/share/ShareSessionCache.java