Add Resource entity

[kovstas]

• fixed the semconv template to access enum values
• added Attributes & Resource classes

It appears that we need to validate attribute values for resources, but I couldn't decide on the appropriate location to do so. It would be better to add a smart constructor for the attribute itself in the following pull requests, rather than adding validation for already created attributes within the resource's constructor.

[iRevive]

Currently, most methods use varargs, e.g:

def resourceSpan[A](name: String, attributes: Attribute[_]*)

I wonder whether we should offer a new alternative too:

def resourceSpan[A](name: String, attributes: Attributes)

[kovstas]

To be honest, I would completely replace Attribute with Attributes. Attribute looks like an unnecessary wrapper to me because, from my perspective, users are more interested in using a collection that provides interfaces for accessing particular values by keys or iterating over all of them. I can imagine that It might be useful as a smart constructor which validates passed values, but the collection can do the same. Maybe I don't see a use-case for it.

[iRevive]

Excellent work! Looks good to me

[armanbilge]

Ross suggests in #199 (reply in thread) that we should target this to main after all. We will use another strategy to break the tracing work into smaller PRs instead.

[kovstas]

Ross suggests in #199 (reply in thread) that we should target this to main after all. We will use another strategy to break the tracing work into smaller PRs instead.

I've added NoPublishPlugin to the sdk-common module.

[armanbilge]

Sorry for the slow review cycle! Had a few more thoughts, but overall looks good!

[iRevive]

Looks good, thanks!

[armanbilge]

Thanks for iterating! Looks good, sorry I still had a few nitpicks but all very minor and non-blocking.