Exception "Attempted to call method hasScope(java.lang.String) on null context object" when using @PreAuthorize with #oauth2

In a @ResourceServer application I have the following rest controller :

@RestController
public class TestApi {
    @RequestMapping("/testScope1")
    @ResponseBody
    @PreAuthorize("#oauth2.hasScope('scope1')")
    public String testScope1() {
        return "You have the scope1 scope!";
    }
}

At runtime, when accessing this endpoint you have the following error : org.springframework.expression.spel.SpelEvaluationException: EL1011E:(pos 8): Method call: Attempted to call method hasScope(java.lang.String) on null context object

In my setup PreAuthorize works otherwise : PreAuthorize(“hasRole(‘ROLE_ADMIN’)”) works for example

The same thing works well if I specify the access in my ResourceServerConfiguration instead of @Controllers’ methods

@Configuration
@EnableResourceServer
public class ResourceServerConfiguration extends ResourceServerConfigurerAdapter {
    @Override
    public void configure(HttpSecurity http) throws Exception {       
        http.authorizeRequests().
            antMatchers("/testScope1").access("#oauth2.hasScope('scope1')").
            anyRequest().authenticated();
    }
}

There is a similar issue discribed here : http://stackoverflow.com/questions/29797721/oauth2-security-expressions-on-method-level