EPAM Systems Java Full Stack Developer interview questions

Recruiter connected through instahyre and scheduled first round technical interview. There will be two technical rounds for Java backend and Full Stack interview. My First Round is completed. These are the questions asked: Internal implementation of LinkedHashMap? Internal implementation of PriorityQueue? Class level locking and object level locking? Can we invoke the terminated collection? Facade design pattern? Liskov substitution principle? Heap data structure? Doubly linkedlist datastructure implementation? [1,3,5,7,8,9], targetSum=13, output=[2,4] indexes of the elements that match the target sum. Find a second non-repeated character from the given string?

Average and Easy going. Interviewer was detail oriented and wanted to understand logic and WHYs behind every answers that you gave. Make sure to give specific answer without giving mugged up answers