@Test public void testToImmutableTable_rowKeysDontHaveToBePreGrouped() {

  ImmutableTable<?, ?, ?> table =
      BiStream.of(
              "r1", BiStream.of("c1", 11),
              "r1", BiStream.of("c2", 12))
          .collect(toImmutableTable());
  assertThat(table.rowMap()).containsExactly("r1", ImmutableMap.of("c1", 11, "c2", 12)).inOrder();
}