What are the consequences of a client-side subscription buffer overflow occurring, i.e. the event that causes the SubscriptionNotificationListener.onBufferOverflow method being called?

The JavaDoc states:

“… Although you get the discarded data in the event, you should not normally try to handle it, since it will not help. But you may record it as a reference.”

I don’t understand this. Will the client automatically attempt to request the data that didn’t fit into the buffer again, or will that data get lost? In the former case, is this listener-method basically only useful in informing the developer that a larger buffer could be more efficient? In the latter case, will the onMissingData listener-method get called as well?