Make task awaitable in rpc continuation readonly

Author: danielmarbach

projects/RabbitMQ.Client/Impl/AsyncRpcContinuations.cs

@@ -46,7 +46,7 @@ internal abstract class AsyncRpcContinuation<T> : IRpcContinuation
         private readonly CancellationTokenSource _continuationTimeoutCancellationTokenSource;
         private readonly CancellationTokenRegistration _continuationTimeoutCancellationTokenRegistration;
         private readonly CancellationTokenSource _linkedCancellationTokenSource;
-        private readonly ConfiguredTaskAwaitable<T> _tcsConfiguredTaskAwaitable;
+        private ConfiguredTaskAwaitable<T> _tcsConfiguredTaskAwaitable;
         protected readonly TaskCompletionSource<T> _tcs = new TaskCompletionSource<T>(TaskCreationOptions.RunContinuationsAsynchronously);
 
         private bool _disposedValue;