public static SqlMap of(final SqlType keyType, final SqlType valueType) {
    return new SqlMap(keyType, valueType);
  }
@SuppressWarnings("UnstableApiUsage")
  @Test
  public void shouldImplementHashCodeAndEqualsProperly() {
    new EqualsTester()
        .addEqualityGroup(SqlMap.of(SOME_TYPE, SOME_TYPE), SqlMap.of(SOME_TYPE, SOME_TYPE))
        .addEqualityGroup(SqlMap.of(OTHER_TYPE, SOME_TYPE))
        .addEqualityGroup(SqlMap.of(SOME_TYPE, OTHER_TYPE))
        .addEqualityGroup(SOME_TYPE)
        .testEquals();
  }