@Override
    public String toString() {
      return String.format("[path = %s, length = %s]", path, length);
    }
Return the list of all files given the stream name
@param streamName name of the stream
@return list of <code>FileMetadata</code> for all files associated to the given stream
samza-hdfs/src/main/java/org/apache/samza/system/hdfs/partitioner/FileSystemAdapter.java