private AtomicInteger get(final T identifier) {
        AtomicInteger entry = map.get(identifier);
        if (entry == null) {
            final AtomicInteger newEntry = new AtomicInteger();
            entry = map.putIfAbsent(identifier, newEntry);
            if (entry == null) {
                entry = newEntry;
            }
        }
        return entry;
    }
Concurrent map of integer counts.

@since 5.0

@param <T> identifier used as a map key
httpclient5-cache/src/main/java/org/apache/hc/client5/http/schedule/ConcurrentCountMap.java