Adding metadata to an observation

[JoeLee99]

Please describe the feature request.
I am trying to capture some metadata for my spans, specifically the param keys and values.

I know I can use the @observed annotation but it looks like it only captures lowCardinalityValues and I'm not sure if you can add in param values to them.

The only way I figured out how to capture the param values is to manually wrap the core logic in my service method in an Observation like this:

public List<Recipes> findRecipes(
            String type,
            List<UUID> ownerIds,
            Boolean includeOwner,
            Boolean includeTested,
            String sort,
            Integer limit
) {
        KeyValues lowCardinalityKeyValues = KeyValues.of(
                "type", String.valueOf(type),
                "includeOwner", String.valueOf(includeOwner),
                "includeTested", String.valueOf(includeTested),
                "sort", String.valueOf(sort),
                "limit", String.valueOf(limit)
        );

        return Observation.createNotStarted("test", observationRegistry)
                .contextualName("findRecipes")
                .lowCardinalityKeyValues(lowCardinalityKeyValues)
                .highCardinalityKeyValue("ownerIds", String.valueOf(ownerIds))
                .observe(() -> recipeDao.findRecipes(
                        type,
                        ownerIds,
                        includeTested,
                        sort,
                        limit
                ));
    }

I am looking for a better way to do this. Previously with Sleuth I was using @SpanTag and that used to work, but not any more.
Rationale
Wrapping all of the logic with an Observation works, but it looks messy and adds quite a bit of code.

Additional context
Add any other context about the feature request here, e.g. related issues, prior art.

[jonatan-ivanov]

This is similar to what we have with @MeterTag, we could have a @...KeyValue... annotation that works the same and also let's you define if the KeyValue is low or high cardinality.

@Observed cannot capture high cardinality values since annotation arguments cannot be dynamic in java.

[jonatan-ivanov]

Do you want to try implementing it and open a PR for this?
For the reference, you can look at @MeterTag (in Micrometer) and @SpanTag (in Micrometer Tracing).

[JoeLee99]

Sure, I would love to give it a go.
Thanks I will look at those repos.