Just speaking to points 1 and 2:

In an interview, there is an unspoken assumption that you won't be using third party libraries to implement algorithms, and certainly not a third party library that implements it in one function call. Using that as a red flag will yield a LOT of false positives.

Also, I have over 10 years experience in Java, have used Apache commons extensively, and had no idea that a string reversal method even existed. You can't use that knowledge to judge anything useful.