How to fix parsing go.mod module declares its path as "x" but was required as "y"
Solution 1:
I had similar issue. I ended up removing the go.mod file in the project I was trying to import and running go mod init ... again. It fixed it.
Also, run go clean -modcache where you are importing.
Then try to go get ... your package.
Solution 2:
I think the problem comes from the fact that the go.mod of your cloned version of original-project still says module github.com/y/original-project. You should use the go.mod replace directive. It is meant for cases like yours exactly.
replace github.com/y/original-project => /path/to/x/my-version