set metadata(agent) { // eslint-disable-line accessor-pairs
    const tx = agent.tracer.getTransaction()
    const attrs = tx?.trace?.custom.get(DESTINATIONS.TRANS_SCOPE) || {}
    for (const [k, v] of Object.entries(attrs)) {
      if (k.startsWith('llm.') === false) {
        continue
      }
      this[k] = v
    }
  }
Pull user set `llm.*` attributes from the current transaction and
add them to the event.

@param {object} agent The New Relic agent that provides access to the
transaction.