How-to Github Actions: Build Matrix - Example Detekt

detekt-build.yml

jobs:
  gradle:
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
        jdk: [8, 11, 14]
    runs-on: ${{ matrix.os }}
    env:
      JDK_VERSION:  ${{ matrix.jdk }}

  steps:
    - name: Checkout Repo
      uses: actions/checkout@v2
    ...
    - name: Setup Java
      uses: actions/setup-java@v1
      with:
        java-version: ${{ matrix.jdk }}