Begin API changes for spiffe/spire#5019

Signed-off-by: Benjamin Leggett <benjamin.leggett@solo.io>

proto/spire/api/agent/delegatedidentity/v1/delegatedidentity.proto

@@ -25,7 +25,7 @@ service DelegatedIdentity {
     //
     // Subscribers are expected to ensure that the PID they use is not recycled
     // for the lifetime of the stream, and in the event that it is, are expected
-    // to close the stream.
+    // to immediately close the stream.
     // TODO do we want this caveat? I think we either have to live with this,
     // _or_ not allow delegates to start subscriptions via PID.
     rpc SubscribeToX509SVIDsByPID(SubscribeToX509SVIDsByPIDRequest) returns (stream SubscribeToX509SVIDsResponse);
@@ -42,6 +42,7 @@ service DelegatedIdentity {
     // for the requested audience.
     // Subscribers are expected to ensure that the PID they use is not recycled
     // from the time this call is made until the time a response is returned.
+    // Failing this, the response must be discarded.
     rpc FetchJWTSVIDsByPID(FetchJWTSVIDsByPIDRequest) returns (FetchJWTSVIDsResponse);
 
     // Subscribe to get local and all federated JWKS bundles.