Spring AspectJ get method annotation from ProceedingJoinPoint

I have an aspect that handles all methods that have a custom annotation.

The annotation has an enum parameter and I have to get the value in the aspect:

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Monitored {
    MonitorSystem monitorSystem();
}

My case is very similar to that question and the accepted answer works for Spring beans that do not implement an interface.

The aspect:

@Aspect
@Component
public class MonitorAspect {

    @Around("@annotation(com.company.project.monitor.aspect.Monitored)")
    public Object monitor(ProceedingJoinPoint pjp) throws Throwable {
        MethodSignature signature = (MethodSignature) pjp.getSignature();
        MonitorSystem monitorSystem = signature.getMethod().getAnnotation(Monitored.class).monitorSystem();
        ...
    }
}

But if the Spring bean that is annotated with @Monitored (only the implementation class is annotated) implements an interface - pjp.getSignature() returns the signature of the interface and it does not have an annotation.

This is OK:

@Component
public class SomeBean {
   @Monitored(monitorSystem=MonitorSystem.ABC) 
   public String someMethod(String name){}
}

This does not work - pjp.getSignature() gets the signature of the interface.

@Component
public class SomeBeanImpl implements SomeBeanInterface {
   @Monitored(monitorSystem=MonitorSystem.ABC) 
   public String someMethod(String name){}
}

Is there a way to get the signature of the implementation method from ProceedingJoinPoint?