What's the recommended way to add metrics to a processor?

[chenlujjj]

Hi, I tried to implement a processor and I wanted to expose some metrics of the processor itself. So what's the recommended way to add metrics to a processor? I was not able to find a guide on that.

The filter processor also has such telemetry: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/processor/filterprocessor/telemetry.go#L18, is it the standard way?