?? BufferBuilder<R,T,U extends BlockingQueue<PushEvent<? extends T>>>

????:
R - The type of object being built
T - The type of objects in the PushEvent
U - The type of the Queue used in the user specified buffer
???????:
PushStreamBuilder<T,U>

@ProviderType public interface BufferBuilder<R,T,U extends BlockingQueue<PushEvent<? extends T>>>
Create a buffered section of a Push-based stream