Persistent Systems interview questions

I was contacted by HR for a face to face Interview in Persistent systems, Hyderabad location, The interview process took me for about 7 hours, I have not been given an offer, but here is my experience Round1 : Technical Interview Basic Technical questions 1. HashMap internal working 2. SpringBootApplication Annotation 3. How are APIs secured in the application 4. Explain the project in detail, project related questions like, which patterns we have used in microservices. 5. ConcurrentModification Exception 6. Program , Given an array, form all possible array combinations i.e.; int[] a = {1,2,3} , o/p: {1,2} , {1,3} . {2,3} I have cleared the first round, I was able to answer all the questions. Round 2: Techno Managerial: This was most trickiest interview for me, may be because my salary was high, I was grilled in this interview. The Manager has asked me about multi threading Questions, Especially the problems faced with Multi threading architecture. I explained about Strategy Design pattern but interviewer is not convinced how we used it in the project, he said interface and strategy pattern are same, what is the use of strategy, I clearly explained him, we have different strategies implemented which will different behaviors, he literally is not convinced. He then asked me about, Facade Pattern, I explained. Then He asked about Service Discovery, I explained that too. I was supposed to be rejected or selected as this is the last round , but the interviewer asked for re take of L2, I have already spent around 6 hours there and almost everybody left by then. Round2 : Technical Mostly spring and spring boot related questions, asked about 1. Spring Profiles 2. How are profiles activated for each profile 3. How are we communicating between microservices 4. Exception handling in spring boot 5. Why we use Properties files and where are different variables and properties stored in your application. 6. How we are reading the values from the properties file 7. They asked about Junit, I was already tired and frustrated by that time, I really could not answer, but they asked about different annotations of Junit, how the data is mocked and how we can read a particular property from a config file into a junit. Later the Manager came out and said,my profile is not matching for the current requirement.