@Test
    void emptyUnary() throws Exception {
        assertThat(blockingStub.emptyCall(EMPTY)).isEqualTo(EMPTY);
        checkRequestLog((rpcReq, rpcRes, grpcStatus) -> {
            assertThat(rpcReq.params()).containsExactly(EMPTY);
            assertThat(rpcRes.get()).isEqualTo(EMPTY);
        });
        await().untilAsserted(() -> assertThat(RequestTargetCache.cachedClientPaths())
                .contains("/armeria.grpc.testing.TestService/EmptyCall"));
    }
Must be at least {@link #unaryPayloadLength()}, plus some to account for encoding overhead.
grpc/src/test/java/com/linecorp/armeria/client/grpc/GrpcClientTest.java