ISAM Software Developer - Trading & Technology interview questions

I was invited to a phone interview. I spoke with a quant who asked a few non-technical questions regarding my CV, past experience and aspirations. Then, I was given a problem to solve writing Java code. After a few days I received a reply asking me to reply a few followup questions, mainly to describe my code. At which point they replied they decided not to continue with the interview process. Unfortunately, they don’t give specific feedback on the coding exercise. This is a shame since I do not know what I did not do right.