Azure DevOps Pipeline Build for "dotnet core with Submodule"

azure-pipelines.yml

resources:
  repositories:
  - repository: self
    checkoutOptions:
      submodules: true
pool:
  vmImage: 'ubuntu-16.04'
  #name: 'your pool name'
trigger:
  batch: true
  branches:
    include:
      - "*"
variables:
  BuildConfiguration: debug
  BuildPlatform: any cpu
  # you can use glob pattern. (dotnet cli discontinue support but pipeline DotNetCoreCLI does)
  Parameters.RestoreBuildProjects: SubmoduleFolder/**/*.csproj
  Parameters.TestProjects: SubmoduleFolder/**/*Tests/*.csproj
  Parameters.PublishProjects: SubmoduleFolder/**/YOUR_PROJECT.csproj
steps:
- task: DotNetCoreInstaller@0
  inputs:
    packageType: 'sdk'
    version: '2.2.100' 
  
- task: DotNetCoreCLI@2
  displayName: Restore
  inputs:
    command: restore
    projects: '$(Parameters.RestoreBuildProjects)'

- task: DotNetCoreCLI@2
  displayName: Build
  inputs:
    projects: '$(Parameters.RestoreBuildProjects)'
    arguments: '--configuration $(BuildConfiguration)'

- task: DotNetCoreCLI@2
  displayName: Test
  inputs:
    command: test
    projects: '$(Parameters.TestProjects)'
    arguments: '--configuration $(BuildConfiguration)'

- task: DotNetCoreCLI@2
  displayName: Publish
  inputs:
    command: publish
    publishWebProjects: false
    projects: '$(Parameters.PublishProjects)'
    arguments: '--configuration $(BuildConfiguration) --output $(build.artifactstagingdirectory)'
    zipAfterPublish: false
    modifyOutputPath: false

- task: PublishBuildArtifacts@1
  displayName: 'Publish Artifact'
  inputs:
    PathtoPublish: '$(build.artifactstagingdirectory)'

vs code extensions notify checkoutOptions is deprecated. Not yet found valid latest way to write.

This won't work, DevOps Pipeline detected as invalid YAML.

steps:
- checkout: self
  submodules: true

microsoft/azure-pipelines-agent#1729 (comment)