Request for demo/example of integration with cmake project.

I'd like to apply reclient to my cmake project, which has a long history and is expensive to migrate to bazel.
Firstly, I would like to test it on a simple cmake project, hence I selected googletest, a small and good cmake project. I expected to spend 1 or 2 days to make it runnable and then switch to a larger cmake project to do a performance benchmark.
However, I was stuck in the very first step, I read through the document but I was still unable to get the simple googltest compiled leveraging my RBE(buildfarm).

It would be very helpful if there's a workable demo so that I can start with it, and then migrate my own cmake project eaisly

by the way, here is the error that I am unable to fix.

> reclient[431db5a6-e765-4678-8d06-01c5b0952c6d]: RemoteErrorResultStatus: rpc error: code = FailedPrecondition desc = Action 1c45238acf50b25d12aaab7a2841310de01054d119440cd60f8ecdaf89067f45/146 is invalid: working directory is not an input directory. details = violations: {
> type: "INVALID"
> subject: "The `Command` of the `Action` was invalid."
> description: "working directory is not an input directory"
> }

I build the cmake project in a typical way:
1, create a build folder in the src root
2, configure it in build
3, build it using cmake --build .. or just make

Start by reproducing the reported workflow with the googletest CMake project: create a build directory, configure it, and run cmake --build .. or make against the stated RBE setup. Investigate the “working directory is not an input directory” error and document a runnable CMake demo; done means a newcomer can build it remotely and follow the migration steps.

Written by the indexing model from the issue text.