This week's book giveaway is in the Programmer Certification forum. We're giving away four copies of OCP Oracle Certified Professional Java SE 11 Programmer I Study Guide: Exam 1Z0-815 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
I have only given Test 285 (and cleared it) but currently am preparing for 286 and 287. There is no specific recommended book for Test 286. But you can refer the following books that are for Test 285 and Test 287. The objectives for 286 and 287 have a lot of things in common.