Help with cfnValidate() error in pipeline?

[ZillaYT]

We use Jenkins pipeline, and use AWS plugins that has a cfnValidate() API https://jenkins.io/doc/pipeline/steps/pipeline-aws/. When I run it on my Cloudformation template,

AWSTemplateFormatVersion: '2010-09-09'
Parameters:
  AlbName:
    Type: String
    Description: 'Parameter to override ALB name'
    Default: ''
  RedirectUrl:
    Type: String
    Description: 'URL to redirect traffic to'
    Default: ''
  SslCertificateArn:
    Type: String
    Description: 'SSL certificate ARN'
    Default: ''
  VPCStackNameParameter:
    Type: String
    Description: 'CloudFormation stack name of the VPC'
    Default: 'ProductionVPC'

Conditions:
  ProdEnvironment:
    !Equals [ !Ref VPCStackNameParameter, 'ProductionVPC' ]
  CertExists:
    !Not [!Equals [!Ref SslCertificateArn, ""]]

Resources:
  Alb:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Condition: CertExists
    Properties:
      Name: !Ref AlbName
      Scheme: 'internet-facing'
      IpAddressType: 'ipv4'
      SecurityGroups:
        -
          Fn::ImportValue:
            !Sub "${VPCStackNameParameter}-ELBSGID"
      Subnets:
        -
          Fn::ImportValue:
            !Sub "${VPCStackNameParameter}-SubnetPublic1ID"
        -
          Fn::ImportValue:
            !Sub "${VPCStackNameParameter}-SubnetPublic2ID"

      LoadBalancerAttributes:
        - Key: idle_timeout.timeout_seconds
          Value: '240'
      Tags:
        -
          Key: Name
          Value: !Sub "${AWS::StackName}-lb"
        -
          Key: Product
          Value: "Zift"

 

I get

com.amazonaws.services.cloudformation.model.AmazonCloudFormationException: Template format error: Every Condition member must be a string. (Service: AmazonCloudFormation; Status Code: 400; Error Code: ValidationError; Request ID: f6f203b9-5593-11e9-833d-1d475e1ca17e) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.handleErrorResponse(AmazonHttpClient.java:1632) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeOneRequest(AmazonHttpClient.java:1304) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeHelper(AmazonHttpClient.java:1058) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:743) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:717) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:699) at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:667) at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:649) at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:513) at com.amazonaws.services.cloudformation.AmazonCloudFormationClient.doInvoke(AmazonCloudFormationClient.java:2733) at com.amazonaws.services.cloudformation.AmazonCloudFormationClient.invoke(AmazonCloudFormationClient.java:2709) at com.amazonaws.services.cloudformation.AmazonCloudFormationClient.executeValidateTemplate(AmazonCloudFormationClient.java:2673) at com.amazonaws.services.cloudformation.AmazonCloudFormationClient.validateTemplate(AmazonCloudFormationClient.java:2648) at de.taimos.pipeline.aws.cloudformation.CFNValidateStep$Execution$1.run(CFNValidateStep.java:141) Finished: FAILURE

What gives?

[ZillaYT]

I wanted to add, if I validate the file via AWS CLI (aws cloudformation validate-template --document file://my_template.yaml) it passes.