1. There are exactly 2 questions in which the explanations include a reference to LinkedList to show a contrast with the behaviour of an ArrayList. (The questions are about ArrayList, which is on the exam.) There is exactly 1 question where the code listing includes LinkedList but the question does not depend on knowing much about LinkedList, which has now been changed.
2. enum is not explicitly mentioned in the objectives but switch statement is. There are exactly 5 questions that refer to enum and they relate only to its usage with in a switch statement. There is exactly 1 question that that refers to enum in relation to valid keywords.
3. There is no question on HashMap. There is exactly one question that contains the word HashMap but the question is about overriding and not about HashMap functionality at all.