docs: public static void readLongSequence(DataInput in, long[] seqnos, int index) throws IOException {
          byte len=in.readByte();
          if(len == 0) {
              seqnos[index]=seqnos[index+1]=0;
              return;
          }
          byte len1=firstNibble(len), len2=secondNibble(len);
          seqnos[index]=makeLong(in, len1);
          seqnos[index+1]=makeLong(in, len2) + seqnos[index];
      }