[feature request] openinference-vercel should respect attributes that have been set already

[mshick]

Is your feature request related to a problem? Please describe.
The openinference-vercel span processor overwrites any attributes that it gets values for. Ideally it would respect already-set values, particularly since the span attributes property is marked as readonly.

The logic here is responsible.

In my fork, I do the following, and it seems to work well:

  const attributes = safelyGetOpenInferenceAttributes({...span.attributes});

  if (attributes) {
    // Append-only, since the attributes are readonly
    for (const [name, value] of Object.entries(attributes)) {
      // Do not overwrite explicitly set values
      if (span.attributes[name] == null) {
        span.attributes[name] = value;
      }
    }
  }

[mikeldking]

Hey @mshick - thanks for the feedback. Still mulling this over since we had not thought about users wanting to override values - I guess more curious about which values you are feeling you need to override (e.g. you feel are inalid)?