IntegrationWebSocketContainer: Make Buffer Overflow Strategy Configurable

[ColoredCarrot]

Within Spring Integration's WebSocket support, ConcurrentWebSocketSessionDecorator, which buffers outbound messages if sending is slow, is used to decorate all websocket sessions in IntegrationWebSocketContainer, the standard entrypoint for using websockets with Integration.

ConcurrentWebSocketSessionDecorator provides the ability to configure three things:

• sendTimeLimit
• bufferSizeLimit
• overflowStrategy since spring-projects/spring-framework@309ffc6

The first two are also configurable in IntegrationWebSocketContainer. However, overflowStrategy is missing.

Suggestion

I'd like to be able to configure overflowStrategy in IntegrationWebSocketContainer, just like the other two options.
This should be possible via a simple setter, analogous to setSendTimeLimit and setSendBufferSizeLimit.

Context

My project's requirements allow me to drop messages if the server can't keep up (UDP-esque).
Currently, when messages aren't being flushed out fast enough, ConcurrentWebSocketSessionDecorator hits its buffer size limit and closes the websocket session.
I wish to use OverflowStrategy.DROP to circumvent this.

A workaround is increasing the buffer size limit, though this is obviously not sustainable.