Run Sonar scan for PRs from forks

I am trying to setup a Github Actions Workflow that runs Sonar analysis for each PR. I have one job that runs unit tests and uploads the test reports. Second job then downloads the reports and runs the analysis. This works fine for my PRs. But workflows triggered by PR from forked repos do not have access to secrets so the sonar is not working there.

I tried to solve this by splitting the workflow in two where sonar part is triggered by workflow_run of the PR. The problem is that no matter what I do, the sonar ignores the test coverage reports and marks PR with "No Coverage information".

Here is the workflow definition I am using.

on:
  workflow_run:
    workflows:
      - Pull request verification
    types:
      - completed
env:
  JAVA_DISTRIBUTION: 'temurin'
  JAVA_VERSION: '17'

jobs:
  pr_sonar_analysis:
    name: PR sonar analysis
    runs-on: ubuntu-latest
    container:
      image: fedora:38
    steps:
      - name: Install dependencies
        shell: bash
        run: dnf --setopt install_weak_deps=False install -y gettext jss unzip tree git

      - name: Check out repository
        uses: actions/checkout@v3

      - name: Download test reports
        uses: actions/github-script@v6
        with:
          script: |
            let allArtifacts = await github.rest.actions.listWorkflowRunArtifacts({
               owner: context.repo.owner,
               repo: context.repo.repo,
               run_id: context.payload.workflow_run.id,
            });
            let matchArtifact = allArtifacts.data.artifacts.filter((artifact) => {
              return artifact.name == "unit_test_reports"
            })[0];
            let download = await github.rest.actions.downloadArtifact({
               owner: context.repo.owner,
               repo: context.repo.repo,
               artifact_id: matchArtifact.id,
               archive_format: 'zip',
            });
            let fs = require('fs');
            fs.writeFileSync(`${process.env.GITHUB_WORKSPACE}/unit_test_reports.zip`, Buffer.from(download.data));            

      - name: 'Unzip artifact'
        run: unzip unit_test_reports.zip

      - name: Set up Java
        uses: actions/setup-java@v3
        with:
          distribution: ${{ env.JAVA_DISTRIBUTION }}
          java-version: ${{ env.JAVA_VERSION }}

      - name: Run sonar
        uses: gradle/gradle-build-action@v2
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
        with:
          arguments: sonar -x coverage
            -Dsonar.scm.provider=git
            -Dsonar.pullrequest.key=${{ github.event.workflow_run.pull_requests[0].number }}
            -Dsonar.pullrequest.base=${{ github.event.workflow_run.pull_requests[0].base.ref }}
            -Dsonar.pullrequest.branch=${{ github.event.workflow_run.pull_requests[0].head.ref }}
            -Dorg.gradle.jvmargs=-Xmx1g

I tried:

• Uploading just the coverage report
• Uploading just jacoco.exec and generating report in sonar job
• Uploading everything in build folder
• Redefining paths where jacoco generates reports and from where sonar reads them
• Running both unit tests and sonar in workflow_run. Even in this case sonar reports "No Coverage information"

Is there something to force sonar to use the coverage I am providing?

Workflow was checking out the wrong branch. After switching branches workflow works as expected.

- name: Check out repository
  uses: actions/checkout@v3
  with:
    repository: ${{ github.event.workflow_run.head_repository.full_name }}
    # checkout commit that triggered this workflow
    ref: ${{ github.event.workflow_run.pull_requests[0].head.ref }}
    fetch-depth: 0