just there so the compiler has to work its 40+ hours too

I would like to point out here, that the last return (return "";) is unnecessary, as there will always be a returned value, no matter the outcome of the if statement.

This is not the best approach, since it has to go through the array three times.

Very neat!

I would just return Array.Empty(), since it's a singleton and does not take extra memory on creating a new array.