@Override
            public void onNext(SimpleResponse value) {
                try {
                    final ClientRequestContext ctx = ClientRequestContext.current();
                    assertThat(value).isEqualTo(goldenResponse);
                    final ByteBuf buf = ctx.attr(GrpcUnsafeBufferUtil.BUFFERS).get(value);
                    assertThat(buf.refCnt()).isNotZero();
                    GrpcUnsafeBufferUtil.releaseBuffer(value, ctx);
                    assertThat(buf.refCnt()).isZero();
                } catch (Throwable t) {
                    resultQueue.add(t);
                }
            }
Must be at least {@link #unaryPayloadLength()}, plus some to account for encoding overhead.
grpc/src/test/java/com/linecorp/armeria/client/grpc/GrpcClientTest.java