code: @Override
    public Iterator<FileSet<CopyEntity>> getFileSetIterator(FileSystem targetFs, CopyConfiguration configuration,
        Comparator<FileSet<CopyEntity>> prioritizer, PushDownRequestor<FileSet<CopyEntity>> requestor)
        throws IOException {
      if (!canCopyTable()) {
        return Iterators.emptyIterator();
      }
      try {
        List<FileSet<CopyEntity>> fileSetList = Lists.newArrayList(new HiveCopyEntityHelper(this, configuration, targetFs)
            .getCopyEntities(configuration, prioritizer, requestor));
        Collections.sort(fileSetList, prioritizer);
        return fileSetList.iterator();
      } catch (IOException ioe) {
        log.error("Failed to copy table " + this.table, ioe);
        return Iterators.emptyIterator();
      }
    }
docs: Finds all files read by the table and generates CopyableFiles.
  For the specific semantics see {@link HiveCopyEntityHelper#getCopyEntities}.