docs: protected Table __union(Table t, int offset) {
      offset += bb_pos;
      t.bb_pos = offset + bb.getInt(offset);
      t.bb = bb;
      t.vtable_start = t.bb_pos - bb.getInt(t.bb_pos);
      t.vtable_size = bb.getShort(t.vtable_start);
      return t;
    }