roxy/tree/master/extensions/stats>implemented</a> as a <a href=https://github.com/proxy-wasm/spec>Proxy-wasm</a> plugin.
A <code>COUNTER</code> is a strictly increasing integer.
A <code>DISTRIBUTION</code> maps ranges of values to frequency.
<code>COUNTER</code> and <code>DISTRIBUTION</code> correspond to the metrics counter and histogram
in <a href=https://github.com/envoyproxy/envoy/blob/main/source/docs/stats.md>the Envoy document</a>.</p><h2 id=metrics>Metrics</h2><p>For HTTP, HTTP/2, and GRPC traffic, 