@Override
    public final Cancellable updateEntry(
            final String key, final HttpCacheCASOperation casOperation, final FutureCallback<Boolean> callback) {
        Args.notNull(key, "Storage key");
        Args.notNull(casOperation, "CAS operation");
        Args.notNull(callback, "Callback");
        final ComplexCancellable complexCancellable = new ComplexCancellable();
        final AtomicInteger count = new AtomicInteger(0);
        attemptUpdateEntry(key, casOperation, complexCancellable, count, callback);
        return complexCancellable;
    }
Abstract cache backend for serialized objects capable of CAS (compare-and-swap) updates.

@since 5.0
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/AbstractSerializingAsyncCacheStorage.java