@Override
    public Set<Map<String, Object>> connectorPartitions(String connectorName) {
        return connectorPartitions.getOrDefault(connectorName, Collections.emptySet());
    }
Implementation of OffsetBackingStore that saves data locally to a file. To ensure this behaves
similarly to a real backing store, operations are executed asynchronously on a background thread.
connect/runtime/src/main/java/org/apache/kafka/connect/storage/FileOffsetBackingStore.java