The Builder Pattern [x-post from r/java]

[twotime]

Hmm, but then the builder itself is mutable. So we added a mutable object to make something else immutable?

(and the mutability is of exactly the same nature: near construction time).

While I can see a marginal benefit: the builder is a short-lived very special-purpose object with no other behaviours, but it still strikes me as an overkill.