public Collection<ShardingSphereConstraint> getConstraintValues() {
        return constraints.values();
    }
@Test
    void assertGetConstraints() {
        ShardingSphereConstraint constraint = new ShardingSphereConstraint("t_order_foreign_key", "t_user");
        ShardingSphereTable table = new ShardingSphereTable("t_order", Collections.emptyList(), Collections.emptyList(), Collections.singletonList(constraint));
        assertThat(table.getConstraintValues(), hasItems(constraint));
        assertThat(table.getConstraintValues(), hasSize(1));
    }