@Override
    public void close() throws IOException {
      if (current != null) {
        closeQuietly(current::close);
      }
      closeQuietly(reader::close);
    }
A simplified wrapper over an {@link HFileBlock.BlockIterator} that looks a lot like an
{@link java.util.Iterator}.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockHeaderCorruption.java