There was 5 rounds of interview. The first round was more of a skype interview, with basic coding interview using a open source tool. I was shortlisted and was asked to report for an onsite interview.
The onsite interview comprised of four rounds. The first round was an interview session with the Senior Director. It was more of a 'tell me about yourself' and 'basic interview questions' related to Java and open source concepts.
Following that, I had an interview session with Distinguished engineer. It was a different interview experience and the questions were entirely different. More of applied engineering concepts and Mathematics in real-time.
The third round was a technical interview having questions entirely in core-java to assess the coding approach and thought process. Asked to solve few questions along with explanation.
The fourth round was also a technical interview without much coding. Involved core Java and few other open source concepts.
Overall, the interview process was to assess how strong the candidate is in basics and how deep is the understanding on OOPS. Few other assessment includes thought process and problem solving approach.