this functionality was performed by Mixer as part of combining request attributes
with the platform data. This metadata exchange is performed by the Envoy proxies
by adding a specific HTTP header for HTTP protocol or augmenting
ALPN protocol for TCP protocol as described
<a href=/v1.17/docs/tasks/observability/metrics/tcp-metrics/#understanding-tcp-telemetry-collection>here</a>.
This requires Envoy proxies to be injected at both the client & server workloads,
implying that the telemetry reported when one pe