There are few places in code where manual `for` loop is used with Iterator to iterate over Collection.
Instead of manual `for` cycles it's preferred to use enhanced-for cycle instead: it's less verbose, makes code easier to read and it's less error-prone.
Sometimes we even don't need cycle at all: we can just create one ArrayList as a copy of another.
It doesn't have any performance impact: javac compiler generates similar code when compiling enhanced-for cycle.