[Multi-project pipelines] Gitlab API does not pass Variables to Downstream project

Problem to solve

I start pipeline in Upstream(Main) project with this command:

curl --request POST --form token=<your_token> \ --form 'variables[DOWNSTREAM_HASH]=origin/some_branch'
https://gitlab.example.com/api/v4/projects/1/trigger/pipeline"

and in Downstream-project .gitlab-ci.yml cant access to variable DOWNSTREAM_HASH from HTTP-request.

Gitlab in Downstream-project inherits value of this variable from hardcoded .gitlab-ci.yml of Upstream(Main)-project. And ignore value from HTTP-request.

I want trigger to pass variables from HTTP to downstream-project.

Further details

I saw ticker #213729 (closed) and docs https://docs.gitlab.com/ee/ci/multi_project_pipelines.html#passing-variables-to-a-downstream-pipeline

But downstreal-pipeline inherits global variables from upstream .gitlab-ci.yml, NOT from HTTP-request as i expected.

Proposal

Permissions and Security

Documentation

Availability & Testing

What does success look like, and how can we measure that?

What is the type of buyer?

Is this a cross-stage feature?

Links / references