The following interface defines two overloaded methods. Both take one parameter where one is of type "java.util.Collection", the other one of "java.util.Set":

public interface MyService {

  void run(Collection<String> values);

  void run(Set<Integer> values);

}

Furthermore a decorator is defined:

@Decorator
public interface MyServiceDecorator {

  @Inject @Delegate
  private MyService delegate;

  void run(Collection<String> values) {
    delegate.run(values);
  }

  void run(Set<Integer> values) {
    delegate.run(values);
  }

}

A client injects an instance of MyService and invokes "run" using a Set of integer values:

  @Inject
  private MyService myService;

  ...
    Set<Integer> values = new HashSet<>();
    myService.run(values);
  ...

It can be observed that the method " void run(Collection<String> values)" is invoked on the decorator - which is wrong. Changing the order of the method declarations in the interface MyService "solves" the problem.