I was reading on this software engineering page about the use of
static methods. However, I'm confused, and maybe it's about the context in which it talks about
static. The idea is, that static is really bad for testing and shouldn't be used.
When creating immutable class, sometimes the constructor is private and a static factory is used to create the object. Even Java's own documentation supports the use of a factory when creating immutable objects.
A more sophisticated approach is to make the constructor private and construct instances in factory methods