syntax in script strings

auto-devops/maven.gitlab-ci.yml

@@ -26,10 +26,10 @@ variables:
 
 debug-vars:
   script:
-    - echo "MAVEN_ACCESS_TOKENS_DISABLED: $MAVEN_ACCESS_TOKENS_DISABLED" 
-    - echo "MAVEN_DEPLOY_DISABLED: $MAVEN_DEPLOY_DISABLED"
-    - echo "CI_COMMIT_BRANCH: $CI_COMMIT_BRANCH"
-    - echo "CI_DEFAULT_BRANCH: $CI_DEFAULT_BRANCH"
+    - 'echo "MAVEN_ACCESS_TOKENS_DISABLED: $MAVEN_ACCESS_TOKENS_DISABLED"'
+    - 'echo "MAVEN_DEPLOY_DISABLED: $MAVEN_DEPLOY_DISABLED"'
+    - 'echo "CI_COMMIT_BRANCH: $CI_COMMIT_BRANCH"'
+    - 'echo "CI_DEFAULT_BRANCH: $CI_DEFAULT_BRANCH"'
 
 # Retrieve Access Token used to retrieve published Maven packages from GitLab Maven Repository
 .maven.deploy_tokens: