@Override
    public boolean isEmpty() {
      return blockKeys.length == 0;
    }
An implementation of the BlockIndexReader that deals with block keys which are plain byte[]
like MetaBlock or the Bloom Block for ROW bloom. Does not need a comparator. It can work on
Bytes.BYTES_RAWCOMPARATOR
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlockIndex.java