public void ChangeMoveDirection(SphereMoveDirection moveDirection)
 {
     MoveDirection = moveDirection;
 }
 public Sphere(SphereId sphereId)
 {
     SphereId      = sphereId ?? throw new ArgumentNullException();
     MoveDirection = new SphereMoveDirection(Vector2.zero);
     Acceleration  = new SphereAcceleration(InitialAcceleration);
 }