 built-in adapters or any out-of-process adapters for mesh extension.</p><p>For built-in adapters, several alternatives are provided:</p><ul><li><code>Prometheus</code> and <code>Stackdriver</code> integrations are implemented as <a href=/v1.16/docs/reference/config/proxy_extensions/>proxy extensions</a>.
Customization of telemetry generated by these two extensions can be achieved via <a href=/v1.16/docs/tasks/observability/metrics/classify-metrics/>request classification</a> and <a href=/v1.16/docs/tasks/o