message: Simplification of Table::is_nullable
  The attribute will always reflect the property directly.
diff: @@ -1183,9 +1183,7 @@ bool Table::is_nullable(ColKey col_key) const
  {
  REALM_ASSERT_DEBUG(valid_column(col_key));
  size_t col_ndx = colkey2ndx(col_key);
  - return m_spec.get_column_attr(col_ndx).test(col_attr_Nullable) ||
  - (m_spec.get_column_type(col_ndx) == col_type_Link &&
  - !m_spec.get_column_attr(col_ndx).test(col_attr_List));
  + return m_spec.get_column_attr(col_ndx).test(col_attr_Nullable);
  }
  bool Table::is_list(ColKey col_key) const
  