o API protocol if provided, otherwise request or connection protocol.</p><pre><code class=language-yaml data-expandlinks=true data-repo=istio>request_protocol: api.protocol | context.protocol | &#34;unknown&#34;
</code></pre></li><li><p><strong>Response Code</strong>: This identifies the response code of the request. This
label is present only on HTTP metrics.</p><pre><code class=language-yaml data-expandlinks=true data-repo=istio>response_code: response.code | 200
</code></pre></li><li><p><strong>Connectio