WebSocket proxy handles upgrades regardless prefix

[franzzua]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the issue has not already been raised

Issue

I have app with existing web sockets that should be handled by existing handlers. And when I add proxy with webSockets enabled these old handlers stop working.
Could you describe, why it's necessary to use only one upgrade handler?

[mcollina]

Can you make an example with code so I can understand your full use case?