title: CloudBuild Trigger: failed unmarshalling build config cloudbuild.yaml: json: cannot unmarshal string into Go value of type []json.RawMessage
body: <p>When I use my <code>cloudbuild.yaml</code> with CloudBuild trigger, it fails with: </p>
  
  <pre><code>failed unmarshalling build config cloudbuild.yaml: json: cannot unmarshal string into Go value of type []json.RawMessage
  </code></pre>
  
  <p>I already reduced my cloudbuild.yaml to </p>
  
  <pre><code>steps:
    - name: "gcr.io/skynet-2359/sonar-scanner"
      waitFor: "-"
      args: [
        "-Dsonar.projectKey=xxx",
        "-Dsonar.sources=./src",
        "-Dsonar.host.url=http://sonarqube....",
        "-Dsonar.login=${_SONAR_TOKEN}"
      ]
  
  substitutions:
    _SONAR_TOKEN: "..."
  </code></pre>
  
  <p>The build works if I use the CLI way to start: </p>
  
  <pre><code>gcloud builds submit --config cloudbuild.yaml .
  </code></pre>