This is a measure to detect cases where an aTLS handshake is performed but the long running call is interrupted, leading to a retry of the init call.
Whenever the grpc connection state reaches ready, we know that the aTLS handshake has succeeded:
> READY: The channel has successfully established a connection all the way through TLS handshake (or equivalent) and protocol-level (HTTP/2, etc) handshaking, and all subsequent attempt to communicate have succeeded (or are pending without any known failure).
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