putAll method
Stores multiple values in the cache with the given keys.
Each value is wrapped in a CacheItem object, which allows for optional expiry.
Throws a CacheException if there is an error storing the data.
Implementation
Future<void> putAll(Map<String, CacheItem<dynamic>> entries) async {
// Default implementation that calls put for each entry
// Subclasses should override this with a more efficient implementation if possible
for (final entry in entries.entries) {
await put(entry.key, entry.value);
}
}