Fix grpc-core ServerListener.transportCreated drop breaking Firestore Java builds

[Copilot]

Apps referencing Xamarin.Firebase.Firestore (transitively Xamarin.Grpc.Core) fail to build with ServerListenerImplementor is not abstract and does not override abstract method transportCreated(ServerTransport) in ServerListener.

Root cause

io.grpc.internal.ServerListener has two abstract methods, serverShutdown() and transportCreated(ServerTransport). The latter was silently dropped because its parameter io.grpc.internal.ServerTransport is unbound — ServerTransport implements io.grpc.InternalInstrumented, which is itself dropped (its getStats() returns an unbound Guava ListenableFuture). Since ServerListener is a *Listener, the generator emits an IServerListenerImplementor ACW (mono/io/grpc/internal/ServerListenerImplementor.java); with transportCreated missing, the ACW overrode only serverShutdown() and failed Java compilation in consumers.

Changes

• source/io.grpc/grpc-core/Transforms/Metadata.xml
  • <add-node> a minimal io.grpc.internal.ServerTransport interface (its three directly-declared methods, omitting the unbound InternalInstrumented base) so the parameter type resolves.
  • <add-node> transportCreated back onto ServerListener.
• config.json — bump Xamarin.Grpc.Core nugetVersion 1.82.0.1 → 1.82.0.2.
• PublicAPI.Unshipped.txt — regenerated: adds IServerTransport, IServerListener.TransportCreated, ServerTransportCreatedHandler.

ServerTransport is not a *Listener, so it gets no Implementor of its own — the minimal stub adds no new ACW and cannot reintroduce a missing-override break.

The generated implementor now overrides both methods:

public void ServerShutdown () { ... }
public IServerTransportListener? TransportCreated (IServerTransport? p0) { ... }

[Copilot]

Pull request overview

This PR fixes a gRPC binding-generation mismatch where io.grpc.internal.ServerListener.transportCreated(ServerTransport) was being silently dropped (due to an unbound ServerTransport type), causing the generated ServerListenerImplementor.java to miss an override and break downstream Android app Java compilation (e.g., via Xamarin.Firebase.Firestore → Xamarin.Grpc.Core).

Changes:

• Reintroduces a minimal io.grpc.internal.ServerTransport interface in metadata so transportCreated(ServerTransport) can be bound again.
• Re-adds ServerListener.transportCreated(...) to keep the managed interface and generated Java implementor in sync.
• Bumps Xamarin.Grpc.Core NuGet revision and updates PublicAPI unshipped surface to include the restored API.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
source/io.grpc/grpc-core/Transforms/Metadata.xml	Adds minimal ServerTransport and restores ServerListener.transportCreated(...) so the *Implementor compiles correctly.
source/io.grpc/grpc-core/PublicAPI/PublicAPI.Unshipped.txt	Reflects the new/restored public API surface (IServerTransport, TransportCreated, related delegate).
config.json	Bumps Xamarin.Grpc.Core nugetVersion to publish the binding fix as a new revision.