protected Map<String, Map<Integer, Character>> makePopulatedMap() {
      Table<String, Integer, Character> table = makeTable();
      populateTable(table);
      return table.rowMap();
    }

    // `protected` to work around b/320650932 / KT-67447 runtime crash
    protected final void populateTable(Table<String, Integer, Character> table) {
      table.put("foo", 1, 'a');
      table.put("bar", 1, 'b');