public static int encodeNull(PositionedByteRange dst, Order ord) {
    dst.put(ord.apply(NULL));
    return 1;
  }
Encode a null value.
@param dst The destination to which encoded digits are written.
@param ord The {@link Order} to respect while encoding {@code val}.
@return the number of bytes written.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/OrderedBytes.java