The public API of Name is immutable, meaning that there are no methods that can be used to change the state of a Name instance once constructed. However, as an implementation detail of how the public constructors populate the fields of the class, they end up calling private api that modifies state repeatedly.

Having only final fields in immutable objects is good house keeping, but unfortunately test coverage is not very high for Name so it is a bit scary to do refactoring work. Getting to, or close to 100% unit test coverage and then update the implementation to allow for using the final modifier with all fields would be a neat contribution in my opinion.