public int getCount(final T identifier) {
        Args.notNull(identifier, "Identifier");
        final AtomicInteger count = map.get(identifier);
        return count != null ? count.get() : 0;
    }
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