int totalChecksumBytes() {
    return totalChecksumBytes;
  }
Return the number of bytes required to store all the checksums for this block. Each checksum
value is a 4 byte integer. <br/>
NOTE: ByteBuff returned by {@link HFileBlock#getBufferWithoutHeader()} and
{@link HFileBlock#getBufferReadOnly} or DataInputStream returned by
{@link HFileBlock#getByteStream()} does not include checksum.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java