public static void updatePartitionCount(String topic, int newPartitionCount) {
        ConcurrentHashMap<String, String> configs = FakeLocalMetadataStore.ALL_TOPICS.getOrDefault(topic, new ConcurrentHashMap<>());
        configs.compute("partitions", (key, value) -> String.valueOf(newPartitionCount));
        FakeLocalMetadataStore.ALL_TOPICS.putIfAbsent(topic, configs);
    }
update partition count for given topic
@param topic topic name
@param newPartitionCount new partition count.
connect/mirror/src/test/java/org/apache/kafka/connect/mirror/clients/admin/FakeLocalMetadataStore.java