public Builder setRows(
          int index, main.Messages.TableRow value) {
        if (rowsBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureRowsIsMutable();
          rows_.set(index, value);
          onChanged();
        } else {
          rowsBuilder_.setMessage(index, value);
        }
        return this;
      }