You cannot overload operators in Java. The < operator only applies to primitive (or numeric) types, not reference types. Since T is a type variable that represents a reference type, you cannot use < on variables of type T. You have to use
if (item.compareTo(bn.item) < 0)
check the value returned and decide to do what you wish with it.
You don’t know what the type T will be but you know that it will be a type that implements Comparable and therefore implements the compareTo() method.