code: public Vector4d normalize(Vector4d dest) {
          double invLength = 1.0 / length();
          dest.x = x * invLength;
          dest.y = y * invLength;
          dest.z = z * invLength;
          dest.w = w * invLength;
          return dest;
      }
docs: /* (non-Javadoc)
  @see org.joml.Vector4dc#normalize(org.joml.Vector4d)