Is there really no built in way to do
Vector3f A = ...;
Vector3f B = ...;
A += B;
Where A is the same A it was with different values.
That being said, what is nessicary to compile the java side of LWJGL. While there should be a differentation between mutation and creation of a independant result, mutation is critical for convience if nothing else. Otherwise I will always have to call You.GetThisVector() which is just a pain.