Spring Boot REST Controller with CRUD

import org.springframework.web.bind.annotation.*;
import org.springframework.http.*;
import jakarta.validation.Valid;
import jakarta.validation.constraints.*;
import java.util.*;

@RestController
@RequestMapping("/api/users")
public class UserController {
    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping
    public List<UserDTO> findAll(
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "20") int size
    ) {
        return userService.findAll(page, size);
    }

    @GetMapping("/{id}")
    public UserDTO findById(@PathVariable Long id) {
        return userService.findById(id)
            .orElseThrow(() -> new ResponseStatusException(
                HttpStatus.NOT_FOUND, "User not found"));
    }

    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    public UserDTO create(@Valid @RequestBody CreateUserRequest request) {
        return userService.create(request);
    }

    @PutMapping("/{id}")
    public UserDTO update(@PathVariable Long id, @Valid @RequestBody UpdateUserRequest request) {
        return userService.update(id, request);
    }

    @DeleteMapping("/{id}")
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public void delete(@PathVariable Long id) {
        userService.delete(id);
    }
}

record CreateUserRequest(
    @NotBlank String name,
    @Email String email,
    @Min(0) @Max(150) int age
) {}

record UpdateUserRequest(
    @NotBlank String name,
    @Email String email
) {}

record UserDTO(Long id, String name, String email, int age) {}