code: public AnnotatedTypeBuilder<X> addToMethod(Method method, Annotation annotation) {
         if (methods.get(method) == null) {
             methods.put(method, new AnnotationBuilder());
         }
         methods.get(method).add(annotation);
         return this;
     }
docs: Add an annotation to the specified method. If the method is not already
  present, it will be added.
  
  @param method     the method to add the annotation to
  @param annotation the annotation to add
  @throws IllegalArgumentException if the annotation is null