Comment 0 for bug 1864180

When deploying Kibana with the default configuration of openstack_cacert being unset, it fails due to an invalid configuration. The error message is both unfriendly and useful:

"message":"child \"elasticsearch\" fails because [child \"ssl\" fails because [child \"certificateAuthorities\" fails because [single value of \"certificateAuthorities\" fails because [\"certificateAuthorities\" must be a string]]]]"}

This is because we set elasticsearch.ssl.certificateAuthorities even when there is no CA cert configured.