docs: public static byte[] readTxnBytes(InputArchive ia) throws IOException {
          try{
              byte[] bytes = ia.readBuffer("txtEntry");
              // Since we preallocate, we define EOF to be an
              // empty transaction
              if (bytes.length == 0)
                  return bytes;
              if (ia.readByte("EOF") != 'B') {
                  LOG.error("Last transaction was partial.");
                  return null;
              }
              return bytes;
          }catch(EOFException e){}
          return null;
      }