Issue not specified properly.

I am a newbie to Java but interestingly this solution runs faster than the StringBuilder. I tried to run them both to see which one runs faster. But I guess its because the string isn't long enough? I am from the Javascript land so I was excited to see this approach since this looks close to JS.

Why not?

Well, I apparently didn't realize "product" in verb means that. Learning something everyday. Thanks!

Maybe english is not your mother language (it isn't mine either) but that's what product means.

Instructions are so off. It didn't even say to multiply elments in the array. I had to figure that out with the test below.

why '00:00' equals to 12:00?

Fixed.

The best I could do without breaking all current solutions for SQL is adding a conditional comment to the SQL description. I hope that's enough.

Weird, it's working fine for me and other 3790 persons on javascript, maybe post your code and mark your post as having spoiler content so we can check what's wrong with it?
If you are talking about SQL, read the post below, maybe it'll help you (but with the correct code it works too). I've modified the kata description to make more clear what's needed in SQL.
When reporting an issue, first, state what language you're talking about, and then give as much information as you can, it's easier to fix or help you that way.