WAF Classic Regional Web ACL has a rule or rule group

# Terraform: Ensure the Web ACL has at least one rule
resource "aws_wafregional_web_acl" "<example_resource_name>" {
  name        = "<example_resource_name>"
  metric_name = "<example_resource_name>"

  default_action {
    type = "ALLOW"
  }

  # Critical: add at least one rule so the Web ACL is not empty
  rules {
    priority = 1
    rule_id  = "<example_resource_id>"
    action {
      type = "BLOCK"
    }
  }
}

# CloudFormation: Ensure the Web ACL has at least one rule
Resources:
  <example_resource_name>:
    Type: AWS::WAFRegional::WebACL
    Properties:
      Name: "<example_resource_name>"
      MetricName: "<example_resource_name>"
      DefaultAction:
        Type: ALLOW
      # Critical: adding any rule to the Web ACL makes it non-empty and passes the check
      Rules:
        - Action:
            Type: BLOCK
          Priority: 1
          RuleId: "<example_resource_id>"  # Rule to insert into the Web ACL