public class LogDirDescription {
    private final Map<TopicPartition, ReplicaInfo> replicaInfos;
    private final Errors error;

    LogDirDescription(Errors error, Map<TopicPartition, ReplicaInfo> replicaInfos) {
        this.replicaInfos = replicaInfos;
    }

    /**
     * A KafkaStorageException if this log directory is offline, 
     * possibly some other exception if there were problems describing the log directory
     * or null if the directory is online.
     */
    public ApiException error() {
        // ...
    }

    /** 
     * A map from topic partition to replica information for that partition 
     * in this log directory.
     */
    public Map<TopicPartition, ReplicaInfo> repliaInfos() {
        return unmodifiableMap(replicaInfos);
    }

    @Override
    public String toString() {
	// ...
    }
}
public class ReplicaInfo {

    private final long size;
    private final long offsetLag;
    private final boolean isFuture;

    public ReplicaInfo(long size, long offsetLag, boolean isFuture) {
        this.size = size;
        this.offsetLag = offsetLag;
        this.isFuture = isFuture;
    }

    /** 
     * The total size of the log segments in this replica in bytes. 
     */
    public long size() {
        return size;
    } 

    /**
     * The lag of the log's LEO with respect to the partition's 
     * high watermark (if it is the current log for the partition)
     * or the current replica's LEO (if it is the {@linkplain #isFuture() future log}
     * for the partition).
     */
    public long offsetLag() {
        return offsetLag;
    }

    /**
     * Whether this replica has been created by a AlterReplicaLogDirsRequest
     * but not yet replaced the current replica on the broker.
     * @return true if this log is created by AlterReplicaLogDirsRequest and will replace the current log of the replica in the future.
    public boolean isFuture() {
        return isFuture;
    }

    @Override
    public String toString() {
        // ...
    }