@Test
    void emptyUnary_grpcWeb() throws Exception {
        final TestServiceBlockingStub stub =
                GrpcClients.builder(server.httpUri())
                           .serializationFormat(GrpcSerializationFormats.PROTO_WEB)
                           .build(TestServiceBlockingStub.class);
        assertThat(stub.emptyCall(EMPTY)).isEqualTo(EMPTY);
    }
Must be at least {@link #unaryPayloadLength()}, plus some to account for encoding overhead.
grpc/src/test/java/com/linecorp/armeria/client/grpc/GrpcClientTest.java