MerkleTree.RowHash maybe a bug.

[Schubert Zhang]

Hi JE,

0.6.6:
org.apache.cassandra.service.AntiEntropyService

I found the rowHash method uses "row.buffer.getData()" directly.
Since row.buffer.getData()  is a byte[], and there may have some junk bytes
in the end by the buffer, I think we should use the exact length.

        private MerkleTree.RowHash rowHash(CompactedRow row)
        {
            validated++;
            // MerkleTree uses XOR internally, so we want lots of output
bits here
            byte[] rowhash = FBUtilities.hash("SHA-256",
row.key.key.getBytes(), row.buffer.getData());
            return new MerkleTree.RowHash(row.key.token, rowhash);
        }


schubert.zh...@gmail.com