@Test
    void emptyStream() throws Exception {
        final StreamRecorder<StreamingOutputCallResponse> responseObserver = StreamRecorder.create();
        final StreamObserver<StreamingOutputCallRequest> requestObserver =
                asyncStub.fullDuplexCall(responseObserver);
        requestObserver.onCompleted();
        responseObserver.awaitCompletion(operationTimeoutMillis(), TimeUnit.MILLISECONDS);

        checkRequestLog((rpcReq, rpcRes, grpcStatus) -> {
            assertThat(rpcReq.params()).isEmpty();
            assertThat(rpcRes.get()).isNull();
        });
    }
Must be at least {@link #unaryPayloadLength()}, plus some to account for encoding overhead.
grpc/src/test/java/com/linecorp/armeria/client/grpc/GrpcClientTest.java