Spring Controller validation of RequestDTO fields as not null is being ignored

I have a Spring Controller with a DTO PlacePixelRequest as the request body in POST request:

@RestController
public class CanvasController {
    @PostMapping("/canvas/pixel")
    public void placePixel(@Valid @RequestBody final PlacePixelRequest placePixelRequest) {
        try {
            canvasManager.placePixel(placePixelRequest);
        } catch (PixelOutOfBoundsException e) {
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Coordinates requested are out of bounds");
        }
    }
}

import javax.validation.constraints.NotNull;


@Data
@ToString
public class PlacePixelRequest {
    @NotNull
    private int x;
    @NotNull
    private int y;
    @NotNull
    private PixelColor pixelColor;
    @NotNull
    private String placedBy;
}

I have put @NotNull on each of the fields, however, requests are going through just fine even without specifying these fields in the request body:

curl --location 'http://localhost:8080/canvas/pixel' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <TOKEN>' \
--data '{
    "x": "0",
    "y": "5"
}'

returns 200 OK.

I have tried looking at different solutions where the suggestion is to check if the @Valid annotation is present on the controller method request body, which is already present in my case.

The other suggestion was to have the validation API on classpath. I already have these two dependencies in my pom.xml:

   <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
    </dependency>
    <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
            <version>2.0.1.Final</version>
    </dependency>
 

If you use spring 3+ you should use this packages.

import jakarta.validation.Valid
import jakarta.validation.constraints.Max
import jakarta.validation.constraints.Min
import jakarta.validation.constraints.NotNull

Take a loot at realese notes from Spring Boot 3 - they changed a lot)