code: @SuppressWarnings("unchecked")
     public <T> void register(String subjectName, SubjectObserver<T> subjectObserver)
     {
        Subject<?> subject = (Subject<?>)this.registry.get(subjectName);
        
        if(subject == null)
           subject = new Topic<T>();
        
        register(subjectName, subjectObserver, (Subject<T>)subject);
        
     }
docs: Add the subject Observer (default Topic implementation may be used)
  @param <T> the class type
  @param subjectName the subject name
  @param subjectObserver the subject observer