OTC Markets Group Java Server side Developer interview questions

First was a phone interview with an engineer. The engineer was nice and arrived on time. We talked about my previous experience and he patiently told me what they do and the tech stack they use. Then I was scheduled for 4 round video interviews. 1st round: The interviewer was later for 7 minutes due to "technique issues" on their side. The interviewer asked some general Java questions. 2nd round: The interviewed did not appear until I told the HR about this ten minutes after the scheduled time began. Also, I was asked some general Java questions and brain teaser. Some questions were already asked in the 1st round. 3rd round: The interviewer was late just like the previous 2 rounds. No technique questions. The interviewer seems unprepared and ended the interview within 15 minutes. After the 3rd interview, I got an email saying that 4th round was cancelled. I was glad that this disorganized interview could end earlier than I expected.