As someone who has been studying for the OCP 8 exam for a while now, could you provide a list of irrelevant chapters or sections from your Java SE 8 Study Guide, that don't matter for the new Java OCP 11 exam.
That's quite a subjective statement! I mean... knowing hashCode()/equals() is no longer part of the OCP 11 objective set.. but I wouldn't call knowing it unimportant!
As Jeanne posted in another thread, if you already have the Java 8 certification guide, then you should take the Java 8 exam. Writing the new book wasn't about the handful of differences between the Java 8 and Java 11 exams.. it was much more substantial. The OCP 11 exams tend to have more detail questions and are a lot more challenging than the OCA 7/8 exams ever were. With that in mind, you should use a Java 11 study guide if you are planning to take the Java 11 exam.
In the ranch wiki, there is a mapping of OCP 8 to OCP 11 part 2 objectives. The table at the bottom shows which objectives no longer map to topics on the exam (ex; fork join framework and LocalDate. (There's lots more; see the link if interested)