Impact of Interface changed?

[lucky6969b]

I am not 100% confident that changing the existing interfaces will not be error-prone.
Should I discard the new changes for ease of use or
Adapt to new changes but having a higher risk of introducing new bugs?

old

///ContactResultCallback is used to report contact points
	struct	ContactResultCallback
	{
		short int	m_collisionFilterGroup;
		short int	m_collisionFilterMask;
		
		ContactResultCallback()
			:m_collisionFilterGroup(btBroadphaseProxy::DefaultFilter),
			m_collisionFilterMask(btBroadphaseProxy::AllFilter)
		{
		}

		virtual ~ContactResultCallback()
		{
		}
		
		virtual bool needsCollision(btBroadphaseProxy* proxy0) const
		{
			bool collides = (proxy0->m_collisionFilterGroup & m_collisionFilterMask) != 0;
			collides = collides && (m_collisionFilterGroup & proxy0->m_collisionFilterMask);
			return collides;
		}

		virtual	btScalar	addSingleResult(btManifoldPoint& cp,	const btCollisionObject* colObj0,int partId0,int index0,const btCollisionObject* colObj1,int partId1,int index1) = 0;
	};

New:

///ContactResultCallback is used to report contact points
	struct	ContactResultCallback
	{
		short int	m_collisionFilterGroup;
		short int	m_collisionFilterMask;
		
		ContactResultCallback()
			:m_collisionFilterGroup(btBroadphaseProxy::DefaultFilter),
			m_collisionFilterMask(btBroadphaseProxy::AllFilter)
		{
		}

		virtual ~ContactResultCallback()
		{
		}
		
		virtual bool needsCollision(btBroadphaseProxy* proxy0) const
		{
			bool collides = (proxy0->m_collisionFilterGroup & m_collisionFilterMask) != 0;
			collides = collides && (m_collisionFilterGroup & proxy0->m_collisionFilterMask);
			return collides;
		}

		virtual	btScalar	addSingleResult(btManifoldPoint& cp,	const btCollisionObjectWrapper* colObj0Wrap,int partId0,int index0,const btCollisionObjectWrapper* colObj1Wrap,int partId1,int index1) = 0;
	};

[Arjay]

The fundamental rule of an interface is that it is generally immutable once published.

So if 'users' are using your interface and you can't force to modify their code, then don't change the interface.

However, if you are the only one that uses the interface and know the spots where you are calling the interface, you are free to change it - this is commonly called 'refactoring'.