#1 key phrase:
java.io — uses decorators. P100 [[ head first design patterns ]]
hasa AND isa — at the same time. MyDecorator instance both HAS-A and IS-A MyDecoratee
Adding features — decorating, while adhering to original interface ie IS-A. MyDecorator.java often adds non-private fields and methods to fulfill the duty of decoration.
Onion — “decoratee” could be abstract or concrete (onion) or an
interface. This onion is very similar if not the same as the RAM-onion
described in other blog posts. P89 [[ head first design patterns ]]
collections Synchronized view — of HashMap is adapter or decorator? I
would say Decorator — interface not changed.
complexity — Compared to straight HAS-A or IS-A, Decoration adds
complexity^flexibility. Due to the added complexity, decorate only
 Private /memebers/ are insigificant in this and many patterns.
Private members are invisible to other objects.