@Override
  public int hashCode() {
    int hash = 0;
    for (ByteBuffer b : this.items) {
      hash += b.hashCode();
    }
    return hash;
  }
Copy the content from this MBB to a byte[] based on the given offset and length the position
from where the copy should start the length upto which the copy has to be done
@return byte[] with the copied contents from this MBB.
hbase-common/src/main/java/org/apache/hadoop/hbase/nio/MultiByteBuff.java