name: Bach.java
on: push
jobs:
  linux:
    name: Linux
    runs-on: ubuntu-latest
    container: openjdk:13
    steps:
    - uses: actions/checkout@v1
    - name: 'Build Bach.java'
      run: ./build.jsh
    - name: 'Install modules into local Maven repository'
      run: source bin/maven-install.sh

name: Bach.java
on: push
jobs:
  linux:
    name: Linux
    runs-on: ubuntu-latest
    steps:
    - name: 'Checkout'
    - uses: actions/checkout@v1
    - name: 'Set up JDK'
      uses: actions/setup-java@v1
      with:
        java-version: 13
    - name: 'Build Bach.java'
      run: ./build.jsh
    - name: 'Install modules into local Maven repository'
      run: source bin/maven-install.sh

Use actions/setup-java instead of a custom container
Use actions/setup-java instead of a custom container
