name: Java CI

on:
  push:
    branches:
    - master
  pull_request:
    branches:
    - master
    
jobs:
  build:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v1
    - name: Set up JDK 1.8
      uses: actions/setup-java@v1
      with:
        java-version: 1.8
    - name: Build with Maven
      run: mvn package --file pom.xml -DskipTests

name: Java CI

on:
  push:
    branches:
    - master
  pull_request:
    branches:
    - master
    
jobs:
  build:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v1
    - name: Set up JDK 1.8
      uses: actions/setup-java@v1
      with:
        java-version: 1.8
    - name: Maven: Download all dependencies
         mvn dependency:go-offline
    - name: Build with Maven
      run: mvn package --file pom.xml -DskipTests

Split out dependency downloading to new step
Split out dependency downloading to new step

For visualization, it helps to not have to search through all the dependency downloads