如何验证@RequestParams不为空？

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

import javax.validation.constraints.NotNull;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @GetMapping("/test")
    public String test(@RequestParam @NotNull String myParam) {
        return "Param is not null: " + myParam;
    }
}

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @GetMapping("/test")
    public String test(@RequestParam String myParam) {
        if (myParam == null || myParam.trim().isEmpty()) {
            throw new IllegalArgumentException("Param cannot be empty");
        }
        return "Param is not null: " + myParam;
    }
}

import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@Validated
public class MyController {

    @GetMapping("/test")
    public String test(@RequestParam @NotNull String myParam) {
        return "Param is not null: " + myParam;
    }
}