Can I use `ST_Buffer` with hibernate and MySql?

I have a question about hibernate-spatial. (I'm using hibernate version 6.1.7.Final)

The official hibernate documentation says that MySql's St_Buffer is not supported,

    @Query("""
            SELECT co
            FROM example AS co
            WHERE st_contains(st_buffer(:center, :radius), co.point)
            """)
    List<CoordinateEntity> findAllWithInCircleArea(@Param("center") final Point center,
                                                   @Param("radius") final int radius);

When I wrote the code like this,

@Test
    void findAllWithInCircle() {
        //given
        final Point point = geometryFactory.createPoint(new Coordinate(20, 10));
        point.setSRID(4326);
        final CoordinateEntity ce1 = repository.save(new CoordinateEntity(point));

        final Point point2 = geometryFactory.createPoint(new Coordinate(40, 40));
        point2.setSRID(4326);
        repository.save(new CoordinateEntity(point2));

        //when
        final List<CoordinateEntity> allContainArea = repository.findAllWithInCircleArea(point,10000);

        //then
        assertSoftly(softAssertions -> {
            assertThat(allContainArea).hasSize(1);
            assertThat(allContainArea.get(0)).isEqualTo(ce1);
            assertThat(allContainArea.get(0).getPoint().getX()).isEqualTo(20);
            assertThat(allContainArea.get(0).getPoint().getY()).isEqualTo(10);
        });
    }

This test code works fine. Doesn't this mean that ST_Buffer is working properly?

When I run the test code, I see that the select is created just fine.

 select
        c1_0.id,
        c1_0.point 
    from
        example c1_0 
    where
        st_contains(st_buffer(?,?),c1_0.point)

I am very confused right now, I was hoping someone could tell me what the X's in the hibernate documentation mean.

I've read and re-read the hibernate documentation, but I don't seem to be getting it right.