Spring Rest Controller inheritance

you can define an abstract method in your abstract class and autowire the correct service on each implementation :

public abstract class CookieApi<T extends Cookie> {

    protected abstract CookieService<T> getCookieService();

    @RequestMapping("/cookieId")
    public void eatCookie(@PathVariable long cookieId) {
        final T cookie = cookieService.findCookie(cookieId); // Cookie service is null
        this.getCookieService().eatCookie(cookie);
    }
}

@RestController
@RequestMapping("/chocolateCookies")
public class ChocolateCookieApi extends CookieApi<ChocolateCookie> {

    @Autowired
    private ChocolateCookie chocolateCookie;

    @Override
    protected CookieService<T> getCookieService() {
        return this.chocolateCookie;
    }

    @PostMapping
    public ResponseEntity<ChocolateCookie> create(@RequestBody ChocolateCookie dto) {
        // TODO Process DTO and store the cookie
        return ResponseEntity.ok(dto);
    }
}

Nikola,

I'm not sure why your code is not working in your system, I created same classes in a project and it is working fine, I even added another Cookie type, service and api classes.

SpringBoot log (you can see 4 end points initialized):

2019-02-26 14:39:07.612  INFO 86060 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/chocolateCookies],methods=[POST]}" onto public org.springframework.http.ResponseEntity<cookie.ChocolateCookie> cookie.ChocolateCookieApi.create(cookie.ChocolateCookie)
2019-02-26 14:39:07.613  INFO 86060 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/chocolateCookies/{cookieId}],methods=[POST]}" onto public org.springframework.http.ResponseEntity<?> cookie.CookieApi.eatCookie(long)
2019-02-26 14:39:07.615  INFO 86060 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/oatmeal-raisin-cookie],methods=[POST]}" onto public org.springframework.http.ResponseEntity<cookie.OatmealRaisinCookie> cookie.OatmealRaisingCookieApi.create(cookie.OatmealRaisinCookie)
2019-02-26 14:39:07.615  INFO 86060 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/oatmeal-raisin-cookie/{cookieId}],methods=[POST]}" onto public org.springframework.http.ResponseEntity<?> cookie.CookieApi.eatCookie(long)

Testing controllers in postman

As @Domingo mentioned, you may have some configuration problems in your application because from OOP and Spring IoC perspectives your code looks fine and runs with no problems.

NOTE: I'm running these controllers using SpringBoot 2.0.5, Java 8, Eclipse

I posted my project in GitHub for your reference. https://github.com/karl-codes/cookie-monster

Cheers!