@Override
        public StreamObserver<SimpleRequest> errorFromClient(StreamObserver<SimpleResponse> responseObserver) {
            return new StreamObserver<SimpleRequest>() {

                @Override
                public void onNext(SimpleRequest value) {
                    responseObserver.onNext(RESPONSE_MESSAGE);
                }

                @Override
                public void onError(Throwable t) {}

                @Override
                public void onCompleted() {}
            };
        }
Must be at least {@link #unaryPayloadLength()}, plus some to account for encoding overhead.
grpc/src/test/java/com/linecorp/armeria/client/grpc/GrpcClientTest.java