public static Projection of(final Collection<? extends SelectItem> selectItems) {
    return new Projection(selectItems);
  }
@Test
  public void shouldImplementEqualsAndHashCoe() {
    new EqualsTester()
        .addEqualityGroup(
            Projection.of(ImmutableList.of(ALL_COLUMNS)),
            Projection.of(ImmutableList.of(ALL_COLUMNS))
        )
        .addEqualityGroup(
            Projection.of(ImmutableList.of(ALL_A_COLUMNS))
        )
        .testEquals();
  }