Is your feature request related to a problem? Please describe.

There isn't any library instrumentation for server side webflux currently. There is instrumentation for the agent, but there's a hole in the current featureset of library instrumentations for spring.

Describe the solution you'd like

There are examples of library instrumentation in Webflux. For example, sleuth's TraceWebFilter.

Something similar to that would be my initial thoughts on a solution.

Additional context

Briefly discussed in slack: https://cloud-native.slack.com/archives/C0150QF88FL/p1671081502211849